Editing King Boo

{{FA}}
{{about|the character debuting in ''[[Luigi's Mansion]]''|his ''[[Super Mario Sunshine]]'' counterpart|[[Big Boo (character)]]}}
{{character infobox
|image=[[File:Mario Party Star Rush King Boo.png|250px]]<br>Artwork from ''[[Mario Party: Star Rush]]''
<!--DO NOT CHANGE THIS TO HIS LUIGI'S MANSION 3 ARTWORK. Please see "Template:character infobox" for more information.-->
|first_appearance=''[[Luigi's Mansion]]'' ([[List of games by date#2001|2001]])
|species=[[Boo]]
|latest_appearance=''[[Super Mario Bros. Wonder]]'' ([[List of games by date#2023|2023]])
}}
{{quote|I am not afraid of [[Luigi|you]], fool! I fear only that infernal [[Poltergust 3000]] you carry on your back! Stupid machine! But I am a KING among [[Boo]]s! I swear it... I shall fear no mere house-cleaning device!!|King Boo|Luigi's Mansion}}
'''King Boo''' is the leader of the [[Boo]]s and [[Ghost (Luigi's Mansion series)|ghosts]], the main antagonist of the [[Luigi's Mansion (series)|''Luigi's Mansion'' series]], and the arch-nemesis of [[Luigi]]. He is also an ally of [[Bowser]] and has aided him in his various schemes. He has succeeded in capturing [[Mario]] in the ''Luigi's Mansion'' games, as well as capturing [[Toad (species)|Toad]]s, [[Professor E. Gadd]], and [[Princess Peach]]. Although not the [[Boohemoth|biggest Boo]], King Boo has some powers throughout the series, including materializing objects and spitting fire. King Boo's power is often directly proportional to the number of Boos in his vicinity.

==History==
===''Luigi's Mansion'' series===
====''Luigi's Mansion''====
{{LM portrait infobox
|image=KingBooGold.png
|width=200px
|full_name=Bowser and King Boo, the Dastardly Duo (GameCube){{ref needed}}<br>King of Boos (3DS)
|age=Unknown
|biography=Nothing is known about this mysterious entity. (GameCube){{ref needed}}<br>
The giant Boo adorned with a crown. It's hard at work on other evil plans involving the other Boos. (Nintendo 3DS)
|room=[[Roof (Luigi's Mansion)|Roof]]/[[Secret Altar]]
|hp=500
}}
[[File:KingBoowser.jpg|thumb|upright=1.1|left|''Luigi's Mansion'' artwork of King Boo escaping from his Bowser suit]]
Prior to the events of ''[[Luigi's Mansion]]'' and its [[Luigi's Mansion (Nintendo 3DS)|remake]], Professor E. Gadd captured [[Boolossus]] in a portrait, using a device called a [[Ghost Portrificationizer]]. He later hung Boolossus's portrait to his Gallery inside [[Professor Elvin Gadd's Lab|his lab]] in [[Boo Woods]]. This angered King Boo, so he devised a plan to rescue Boolossus.

King Boo and his forces attacked the laboratory. The Boos reversed the settings of the Portificationizer and released Boolossus. King Boo then ordered that all the ghosts that E. Gadd had captured should be released as well. After releasing all the portrait ghosts, King Boo created a [[Luigi's Mansion (location)|huge mansion]] and placed it next to the professor's lab. King Boo, his Boo minions, and the recently freed portrait ghosts decided to inhabit the mansion. With a huge mansion and an army of ghosts, King Boo decided to exact revenge upon Mario and Luigi for all the Boos they attacked during their adventures by capturing them.

Hoping to capture Luigi, King Boo sends him a letter. The message states that Luigi has won a mansion in a contest and provides the location of the prize. Luigi asks his brother Mario to investigate the mansion and says that he is arriving shortly thereafter. Mario travels to the mansion, but right after he enters, he is instantly overwhelmed by King Boo's forces and captured. King Boo then imprisons Mario in a portrait, and places him in the [[Secret Altar]], located in the basement of the mansion.

While waiting for Luigi, King Boo and his Boo minions wait behind a secret door in the floor of the [[Storage Room (Luigi's Mansion)|Storage Room]]. When Luigi enters the room and reveals the secret door, the Boos spring out from the floor. However, the Boos (including King Boo) stop their surprise attack when they notice the [[Poltergust 3000]] on Luigi's back, which he had been given from E. Gadd in order to recapture the Portrait ghosts and save his brother. In fear of the device, King Boo and the other Boos scatter and hide in the mansion. King Boo travels to the Secret Altar in the mansion's basement.

The special key that [[Vincent Van Gore]] holds unlocks the path to the Secret Altar. However, he is locked in [[The Artist's Studio]] on the third floor of the mansion. After capturing him and retrieving the key, Luigi discovers that he still cannot enter the Secret Altar. If Luigi attempts to enter the Secret Altar without catching a certain number of Boos, King Boo blows Luigi to the [[Foyer (Luigi's Mansion)|Foyer]], the entrance of the mansion. Since King Boo's power is related to the number of Boos in the mansion, Luigi can weaken him by capturing the Boos hidden in various rooms. After Luigi captures at least forty of the mansion's fifty Boos, King Boo loses his ability to blow Luigi from the Secret Altar. Once King Boo is weakened, Luigi enters King Boo's Secret Altar.

[[File:LM 3DS Bowser King Boo.png|thumb|left|King Boo's boss fight in the 3DS remake]]
Upon entering the Altar, Luigi notices King Boo staring at Mario in the painting while insulting the brothers' intelligence for having fallen for his scheme. King Boo then turns around to face Luigi and states his desire to add a Luigi painting to the collection. After this, King Boo flies into the Mario painting hanging on the wall. The picture of Mario transforms into Bowser, then the new Bowser painting inhales Luigi into the canvas, transporting Luigi into an arena that resembles the mansion's [[Roof (Luigi's Mansion)|roof]]. Luigi then confronts Bowser. In reality, this is a suit of Bowser that King Boo controls from the inside and uses as a shield.

King Boo uses this Bowser suit to attack Luigi, shooting flames at him causing ten HP of damage, and even attempting to inhale him into its mouth, deducting fifteen HP upon spitting him out. The suit also has the ability to create three large spiked bombs and toss them at Luigi, which when exploding, take away ten HP. Luigi can use his Poltergust 3000 to grab one of the spiked explosives and release it into the Bowser suit's mouth. This attack blasts the head off of the Bowser suit, causing King Boo to exit the shield and expose himself to the Poltergust 3000. Luigi begins to deplete the ghost's five hundred hit points. Meanwhile, the suit's head hovers around the arena, shooting icy blasts at Luigi, which freezes him briefly. King Boo, after a while, flies back into the dormant Bowser body and the head reattaches itself, resuming the fight. Luigi repeats this process, slowly weakening King Boo, but after King Boo's life falls below two hundred HP, the head of the suit reattaches backwards whenever he returns to the Bowser body, causing the Bowser suit to run around aimlessly. The suit soon corrects its head and resumes the fight. Eventually, Luigi manages to completely drain King Boo's HP and capture him inside the Poltergust 3000.

After the battle, Luigi receives King Boo's crown, worth 5000G, and adds it to his treasure collection. Upon returning to the mansion, Luigi quickly travels to Professor E. Gadd's lab. In the lab, Luigi connects the Poltergust to the professor's Portrificationizer, dumping its contents into the machine. Both King Boo and the fake Bowser appear on the Portificationizer portrait. With King Boo captured, Professor E. Gadd hangs [[Portrait ghost|his new portrait]] in an empty room in his gallery.
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====''Luigi's Mansion: Dark Moon'' / ''Luigi's Mansion 2 HD''====
[[File:King Boo Artwork - Luigi's Mansion Dark Moon.png|thumb|Artwork depicting King Boo's redesigned appearance for ''Luigi's Mansion: Dark Moon'']]
King Boo reappears in ''[[Luigi's Mansion: Dark Moon]]'' as the main antagonist and final boss once more. He looks similar to his original appearance from ''Luigi's Mansion'', but he retains the full set of teeth and sped-up voice he had in his appearances in the other ''Super Mario'' titles and is also much larger. He has a purple tongue and mouth and glowing purple eyes, and the dark area around his eyes is bigger and darker.

It is revealed later in the game that [[Professor E. Gadd]] had sold the portrait of King Boo from ''[[Luigi's Mansion]]'' at a garage sale (a car boot sale in British English versions), which is how the king escaped. King Boo shatters the [[Dark Moon]] into six pieces with a bolt of energy from his crown, which contained a power-enhancing gem. This turns the once-friendly ghosts of [[Evershade Valley]] hostile and mischievous as well as sprawling the Dark Moon's pieces to each Mansion of the valley, which Luigi has to recover. 

Towards the end of the game, it is revealed that King Boo has captured Mario like he did in the last game. After Luigi obtains the last Dark Moon piece and returns to the [[Bunker]], King Boo captures him and pulls him back into [[??? (Luigi's Mansion: Dark Moon)|his dimension]]. He reveals to Luigi he escaped from the painting and broke the Dark Moon, causing the ghosts to become under his control. He intends to use the ghosts as an army to conquer both Evershade Valley and the [[Mushroom Kingdom]] while also planning to put Luigi, E. Gadd, and all their friends into paintings for revenge. He then engages into battle with Luigi.

During the final battle, King Boo summons a series of magic lightning bolts with his crown and will attempt to slam Luigi with his body. The latter causes [[Spike Ball|spiked ball]]s to fall from above, which will roll around the tilting platform to pose a hazard. King Boo will stop moving when looked at, and when caught underneath a falling ball he will become stunned, leaving him vulnerable to the [[Poltergust 5000]]. Once his HP is depleted and he gets sucked into the Poltergust 5000, he immediately breaks out and sends Luigi into a floating hallway. He then swells to a large size and begins rolling after Luigi, attempting to stall Luigi with various obstacles, such as falling shelves and suits of armor with large polearms. If King Boo does hit Luigi, he'll pause for a moment to laugh maliciously. Once Luigi makes it out of the hall, he will land on another tilting platform, where King Boo will repeat his previous patterns at a higher intensity. The battle concludes after the third battle and second hallway chase, leading to King Boo's defeat and being sucked into the Poltergust 5000.

====''Luigi's Mansion Arcade''====
King Boo is the final boss for ''[[Luigi's Mansion Arcade]]'', leading his ghosts in an uprising to get revenge on Luigi and Professor E. Gadd. However, after Luigi has sucked in all of his minions with the [[Poltergust 5000]], King Boo assaults Luigi on the [[Terrace (Luigi's Mansion: Dark Moon)|terrace]] of the [[Treacherous Mansion]]. Protected by a magical barrier, he can only be attacked once he lets his guard down. King Boo throws bombs at the player, moves very quickly and clones himself multiple times over the course of the fight. However, only the original has the power-enhancing gem on his crown. Just like in ''Luigi's Mansion: Dark Moon'', he escapes the Poltergust 5000 two times before being defeated for good.

====''Luigi's Mansion 3''====
[[File:LM3 E3 screen 04.png|thumb|left|King Boo chasing Luigi down a hallway in ''Luigi's Mansion 3'']]
King Boo reappears in ''[[Luigi's Mansion 3]]'' with the same design as in ''Luigi's Mansion: Dark Moon'', but with more detail on his crown and a more expressive scowl. King Boo is one of the two main antagonists, having been released by the other main antagonist [[Hellen Gravely]], the owner of [[The Last Resort]] hotel and a big fan of his, in order to impress him. Seeking revenge on Luigi for his previous defeats, he traps Professor E. Gadd, Mario, [[Princess Peach]], and the three [[Toad (species)|Toads]] in portraits before going after Luigi, who manages to escape his capture by going down a laundry chute. He later ends up entrusting Hellen Gravely with Mario's portrait, although it's implied that he intended for Luigi to win both due to Gravely's failures by that time and so he could capture both alongside Peach by using the latter as bait, also recapturing the Toads and Professor E. Gadd just after Mario was freed. However, he ultimately fails to capture Luigi atop the hotel due to [[Polterpup]] shoving him out of the way of King Boo's portrait, and then proceeds to battle Luigi. To defeat King Boo, Luigi must throw a bomb from a spiked ball King Boo throws into his mouth, then pull on his tongue with [[Gooigi]]'s help and slam him repeatedly. Upon doing so, King Boo will then generate a clone that attacks alongside him. After this is done twice, King Boo will enlarge the painting, and Luigi will then have four minutes to attack King Boo one last time. The battle ends with King Boo being recaptured by Luigi and placed in a containment jar alongside Gravely, much to his frustration. As the purple gem in his crown was taken by Luigi after the final battle, it is missing from his crown.<ref>{{cite|author=ProsafiaGaming|date=October 30, 2019|url=youtu.be/GYyMEi0iTZw?t=643|title=Luigi's Mansion 3 - All Endings & Ranks + Credits|publisher=YouTube|accessdate=November 20, 2019}}</ref>

The clones that King Boo summons in the final battle reference his original design from ''Luigi's Mansion'', as they only have two teeth, lacking the middle two fangs King Boo is depicted with now.

If the player gets a game over at any point during this game, King Boo will be shown trapping Luigi in a portrait alongside the rest of his friends.

===''Super Mario-kun''===
[[File:KingBoo SuperMarioKun.jpg|thumb|A depiction of King Boo in ''Super Mario-kun'']]
King Boo appears in a short chapter on ''Luigi's Mansion'' of volume 26 of ''[[Super Mario-kun]]''. As in the game, Luigi reveals King Boo by knocking off the Bowser illusion's head. Unlike in the games, however, King Boo is immediately sucked in.

===''Mario Kart'' series===
====''Mario Kart: Double Dash!!''====
[[File:Petey Piranha and King Boo - Mario Kart Double Dash.png|left|thumb|175px|King Boo and Petey Piranha are partnered racers in ''Mario Kart: Double Dash!!'']]
King Boo is an unlockable character in ''[[Mario Kart: Double Dash!!]]'', marking his first playable appearance. He is partnered with [[Petey Piranha]], and both are unlocked by winning the [[Star Cup]] in Mirror Mode. His large size makes him a heavyweight driver, despite King Boo being a ghost. He and Petey Piranha can use almost any other character's [[Special Item (Mario Kart series)|Special Item]], barring the [[Green Fireball]] or the [[Birdo's Egg]]. The special item they obtain depends on their current position in the race. King Boo's personal kart is the [[Boo Pipes]], which is a gray version of Petey's [[Piranha Pipes]] kart, but with an image of a Boo instead of a Piranha Plant where the item-using partner stands. Additionally, it notably has a low speed stat and high acceleration stat, in contrast with the other heavyweight karts in the game. King Boo appears to slightly shrink when he becomes the driver. On the second "Thanks for Playing!" screen, King Boo appears in the background chasing [[Wario]] and [[Waluigi]].

In the {{media link|MarioKartDoubleDashDebugMenuBossTeresa.png|debug menu}} found in the demos and debug build of the game, King Boo is referred to as "Boss Teresa", the Japanese name used for the [[Big Boo (character)|Big Boo]] boss from ''[[Super Mario 64]]'' and ''[[Super Mario Sunshine]]'', instead of his usual name "King Teresa".

====''Mario Kart DS''====
In ''[[Mario Kart DS]]'', King Boo, along with six other bosses from ''Super Mario 64 DS'', re-appears as one of the bosses of the Mission Mode. King Boo is the boss of the fourth level, with the playable character being [[Princess Peach|Peach]]. Peach attempts to collect 50 [[coin]]s on the [[Lava Arena]] within the time limit, but after a few seconds King Boo appears, surrounds her, and then attacks her, stealing ten of her coins and making all uncollected coins disappear, before teleporting to another area of the arena. To take them back, Peach has to drive and bump into King Boo, making him transparent. Then, she can drive through him again, retrieving her coins and making the other coins reappear. However, King Boo soon reappears a few moments later to get the coins again. After collecting all fifty coins, Peach finally defeats King Boo. Additionally, the [[Bowser]] and King Boo painting from ''[[Luigi's Mansion]]'' appears in the [[DS Luigi's Mansion|Luigi's Mansion]] race course, although only Bowser can be seen in the painting.

====''Mario Kart Arcade GP 2''====
A large picture of King Boo appears near the end of the [[Yoshi Park 2]] course in ''[[Mario Kart Arcade GP 2]]'', where it inhales many ghosts and the racers. As the player drives into his mouth, they are warped back to the beginning of the course.

====''Mario Kart Wii''====
[[File:MKW SNES Ghost Valley 2 Screenshot 2.png|thumb|left|King Boo in ''Mario Kart Wii'']]
King Boo returns in ''[[Mario Kart Wii]]'' as a large-sized driver, and is unlocked by completing the [[Star Cup]] in 50cc. He is also unlocked by playing 750 races. He features a good handling bonus and a small off-road bonus, which comes in handy for vehicles like the [[Offroader]], [[Wario Bike]], and [[Phantom (bike)|Phantom]]. He is used as the Staff Ghost on the {{classic-link|SNES|Ghost Valley 2}} course. In the credits, he appears driving the [[Jetsetter]] on the {{classic|SNES|Ghost Valley 2}} course.

King Boo is one of the few characters to have his standing animation on the character select screen altered from ''Mario Kart: Double Dash!!'' In this case, his tongue is not sticking out of his mouth the whole time like before; now, before selecting him, his tongue is still in his mouth. Other characters whose poses were altered include: [[Yoshi]], who is now looking at the screen; [[Birdo]], whose bow was made larger; [[Diddy Kong]], who is looking in a different direction; Wario, who now has short sleeves; Waluigi, who now performs a slightly different animation when selected; and [[Donkey Kong]], whose mouth is not as wide open and is looking in another direction.
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====''Mario Kart 8 Deluxe''====
[[File:MK8D King Boo Battle Mode Screenshot.png|thumb|King Boo in ''Mario Kart 8 Deluxe'', wearing a crown from [[Battle Mode]]]]
King Boo returns as a playable character in ''[[Mario Kart 8 Deluxe]]'', the enhanced port of ''[[Mario Kart 8]]'' released for [[Nintendo Switch]]. He is among the lightest of the five heavyweight groups, sharing his statistics with [[Rosalina]], [[Link]], and [[Pauline]]. He has the lowest top speed and weight of all the heavyweights, all while sharing similar acceleration as other heavy groups. However, his handling is amongst the best of the heavyweights (shared with the [[Metal Mario|metal]] [[Pink Gold Peach|characters]] and Petey Piranha). He also has the strongest mini-turbo boost of the heavyweights. Finally, his traction stat is noticeably strong, being far and away the best in his weight class, and the third best base traction stat in the game. Additionally, his horn sound is the sound that [[Big Boo (character)|King Boo]] from ''[[Super Mario Sunshine]]'' makes when hit by a [[pepper]]. He is the 150cc Staff Ghost for {{classic-link|GBA|Boo Lake}} and the 200cc Staff Ghost for three courses: [[Twisted Mansion]], {{classic-link|GBA|Snow Land}}, and {{classic-link|3DS|Rosalina's Ice World}}. Initially, King Boo did not have a [[rival]] character for Grand Prix mode, but upon release of Wave 5 of the ''[[Mario Kart 8 Deluxe – Booster Course Pass|Booster Course Pass]]'' DLC, King Boo was given a rival in the form of [[Petey Piranha]] and also became Petey's rival, likely a nod to their status as partners in ''[[Mario Kart: Double Dash!!]]'' Because of this, he is the only base game character to gain a rival through the ''Booster Course Pass''.

====''Mario Kart Arcade GP DX''====
King Boo appears as a featherweight playable character in ''[[Mario Kart Arcade GP DX]]'', sharing his stats with [[Baby Mario]] and [[Baby Peach]]. He was originally only playable during a limited-time event campaign held between October 18, 2017, and January 10, 2018, in the Japanese version, though Bana Passport users could unlock King Boo permanently when they collected three in-game stamps, making him usable even after the event's duration. In an update released on October 10, 2018, he was made available for players who did not participate in the aforementioned event.

====''Mario Kart Tour''====
[[File:MKT King Boo Luigi's Mansion.jpg|thumb|left|170px|King Boo (Luigi's Mansion) in ''Mario Kart Tour'']]
King Boo reappears as a playable character in ''[[Mario Kart Tour]]'', available as of the 2019 [[Halloween Tour (2019)|Halloween Tour]]. He is classified as a Super driver, and his [[Special skill (Mario Kart Tour)|special skill]] is the [[Lucky Seven]].

The game also features two other playable variants of King Boo. '''King Boo (Luigi's Mansion)''', also introduced to the game in the 2019 Halloween Tour, uses his design from ''Luigi's Mansion 3'', marking the first time King Boo is playable using his appearance from the ''Luigi's Mansion'' series. This variant is listed as a High-End character and has the [[Bob-omb Cannon]] special skill. '''King Boo (Gold)''' was introduced for the 2020 [[Halloween Tour (2020)|Halloween Tour]], sporting a golden body and blue-jeweled silver crown. Also listed as a High-End driver, he uses the [[Coin Box]] as his special skill and, like other metallic characters, a distorting filter is applied to his voice. Unlike most characters, King Boo's head icon is recycled from ''Mario Kart 8 Deluxe'', rather than having a new one that uses his in-game model. Similarly, the head icons for his ''Luigi's Mansion'' and gold counterparts also use their in-game artwork.

In pre-release materials, including the [[List of Mario Kart Tour pre-release and unused content|beta test]], King Boo was classified as a Super Rare (High-End) driver and his special skill was the [[Double Bob-ombs]], sharing his change in classification between the beta test and final game with Rosalina.
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===''Super Mario'' series===
====''Super Mario 64 DS''====
{{quote|Eee hee hee! I am Big Boo, the spookiest of all the spirits! I locked up the [[Luigi|wimpy green moustache man]]. And I'll do the same to [[Mario|you]]! Eee hee hee! Since I'm a ghost, I can turn invisible in the mirror's reflection. You'll have to attack me from behind to defeat me. But you'll die of fright before that ever happens! And then you'll be one of us!|King Boo|Super Mario 64 DS}}
[[File:King Boo SM64DS boss fight.png|thumb|Mario engaged in battle with King Boo in ''Super Mario 64 DS'']]
King Boo<ref>{{cite|title=''Nintendo Power'' Volume 188|date=February 2005|page=79|publisher=Nintendo of America|language=American English|quote=(Luigi’s being held captive by King Boo, so you’ll have to rescue him first.)}}</ref> appears in ''[[Super Mario 64 DS]]'', imprisoning [[Luigi]] behind a [[painting]] in [[Big Boo's Haunt]]. When [[Mario]] enters the [[Big Boo Battle]] level to save Luigi, King Boo greets him. From there, the player must listen for King Boo's cackle and enter the door where it is loudest. Eventually, the player reaches the end and fights King Boo to free Luigi. To defeat King Boo, the player has to follow King Boo's movements in the arena's mirror and [[stomp]] him when he comes close enough. Defeating him results in King Boo giving out the [[Luigi Key]]. The player can fight him again as different characters, notably Luigi (who can be fought before unlocking him with [[Luigi Cap|his cap]]) and [[Wario]]. When Luigi meets King Boo, he is confused but proceeds to attack him anyway. When Wario fights him, King Boo is alarmed by his appearance and attempts to scare and attack him. 

In {{wp|Western world|Western}} releases, King Boo is incorrectly called [[Big Boo (character)|Big Boo]], even though he would appear to be different from the Big Boo of Big Boo's Haunt. Internally, they use the same model, with a modifier denoting the presence of the crown.

====''New Super Luigi U'' / ''New Super Mario Bros. U Deluxe''====
King Boo makes a small cameo in ''[[New Super Luigi U]]'' and ''[[New Super Mario Bros. U Deluxe]]'' in the secret exit of [[Vanishing Ghost House]], where his art from ''Luigi's Mansion: Dark Moon'' can be seen in the form of a sign hanging from the side of the building.

====''Super Mario Bros. Wonder''====
[[File:SMBWKingBoo.png|thumb|left|King Boo in ''Super Mario Bros. Wonder'']]
In ''[[Super Mario Bros. Wonder]]'', King Boo appears in the levels [[Light-Switch Mansion]] and [[The Final Battle! Bowser's Rage Stage]], where he chases the player(s) in a similar manner to [[Boohemoth]] in ''[[New Super Mario Bros. 2]]''.<ref name=CM>{{cite|language=ja|author=Nintendo 公式チャンネル|date=September 28, 2023|url=youtu.be/SiLFeqd99cw|title=スーパーマリオブラザーズ ワンダー CM ワンダー篇|publisher=YouTube|accessdate=September 28, 2023}}</ref> In Light-Switch Mansion, King Boo appears once the [[Wonder Flower]] is collected and the [[Wonder Effect]] "A Night at Boo's Opera" is activated. King Boo then chases the player(s) through the level while singing with an operatic baritone voice. If he is looked at, he will cover his face and continue singing, albeit with a voice distortion filter. Once the [[Wonder Seed]] is collected, King Boo's crown will fall off as he shrinks into a regular Boo.<ref>{{cite|author=YTSunny|date=October 19, 2023|url=youtu.be/KWRFFbE5OXc|title=Super Mario Bros Wonder - All Songs / Music Levels|language=en|publisher=YouTube|accessdate=November 4, 2023}}</ref> In The Final Battle! Bowser's Rage Stage, King Boo appears once the player(s) reach the Jack-o-Lantern pumpkins, acting as he does in the other level. Once players enter the zero-gravity section, King Boo again loses his crown and shrinks into a regular Boo, although he floats away off-screen surrounded with music notes.<ref>{{cite|author=Mixeli|date=October 19, 2023|url=youtu.be/jRiP86jxIME|title=Super Mario Bros. Wonder - Final Boss Bowser Battle and Ending (HQ)|publisher=YouTube|accessdate=November 4, 2023|language=en}}</ref>

===''Mario Baseball'' series===
====''Mario Superstar Baseball''====
King Boo is a default playable character in ''[[Mario Superstar Baseball]]'' and appears as a member of [[Wario]]'s baseball team, the [[Wario Greats]]. As a Power type character, he is capable of hitting long outfield drives and even home runs. However, like Boo, his hits are usually very curved, resulting in hitting fouls plenty of the time. Aside from good batting, King Boo has average pitching and fielding, and is a slow runner. His ability is Super Jump, allowing him to catch high balls in the outfield. King Boo has good chemistry with [[Boo]] and [[Petey Piranha]], and he has bad chemistry with [[Luigi]] and [[Baby Luigi]]. Additionally, he wields a Boo-like baseball bat that sports a physical crown on the end of it.

====''Mario Super Sluggers''====
[[File:MSS King Boo Batting Screenshot.png|thumb|left|King Boo batting at [[Yoshi Park]] at night in ''Mario Super Sluggers'']]
King Boo returns as a default playable character in ''[[Mario Super Sluggers]]''. He is once again a default member of Wario's team, the Wario Muscles, making him and Boo the only team players to still be on Wario's team, alongside the captain Wario and sub-captain [[Waluigi]]. He has similar stats to the previous game, although his pitching is improved and matches his batting power. As well, his ability is now Teleport, which activates during close plays, allowing him to teleport safely onto the base when successful. In this game, he has good chemistry with Petey Piranha, Boo, [[Wiggler]], and [[King K. Rool]], but he has bad chemistry with [[Mario]], Luigi, [[Yoshi]], [[Baby Mario]], Baby Luigi, [[Baby Peach]], and [[Baby Daisy]]. His baseball bat also no longer has a physical crown on it, instead having a crown emblem above the Boo emblem on his bat. Additionally, in this game only, the colors of the jewels on King Boo's crown are reversed.

In Challenge Mode, King Boo appears immediately after the player defeats [[Bowser Jr.]] at the [[Wario City]] stadium, stating that he turned invisible and was watching the whole game. However, he is uninterested in joining the player's team unless the team has some Boos with them. This is accomplished by both recruiting Boo and finding the [[Mini Boo]] item.
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===''Super Princess Peach''===
[[File:Shriek Mansion 3-6.png|thumb|[[Princess Peach]] battling King Boo in ''Super Princess Peach'']]
King Boo aids Bowser in ''[[Super Princess Peach]]'' by appearing as the boss of [[Shriek Mansion]]. After adventuring through [[Vibe Island]], Peach discovers where King Boo is and engages him in combat. During the battle, King Boo fires blue homing [[fireball]]s at Peach and chases her regardless of whether she looks at him or not. Peach can damage King Boo with direct light, which is made by having his own flames light the candles spread throughout the room. After a few attacks, King Boo uses his [[Gloom]] vibe, which causes him to cry, which extinguishes the candle flames. After enough attacks, King Boo is eventually defeated. With King Boo eliminated, Peach rescues the Toad and continues against Bowser's forces.

===''Mario Party'' series===
====''Mario Party 8''====
In ''[[Mario Party 8]]'', King Boo gives out [[Star (Mario Party series)|Stars]] on his own board [[King Boo's Haunted Hideaway]]. He hides in one out of three altars and gives the player a Star for ten coins if they can find him where he is hiding. If the player is able to buy the Star, he starts to "summon the bizarre" and disappears, causing the player to jump into a [[Warp Pipe]] that returns them to the starting point. This "makeover mojo" causes the whole layout of the course to change. However, if they do not have enough coins, King Boo causes a pitfall to appear under the player, causing them to return to the starting point and allowing the next player that reaches him to buy the Star. Additionally, if the player fails to steal anything from the board event Pickpocket Pinball, the hosting [[Little Mouser|mouse]] sounds like King Boo. The player can purchase King Boo sounds from the [[Fun Bazaar]], along with a figurine titled "King Boo's Revenge". When the player presses {{button|wii|A}} on the figurine during the Figurine Parade, King Boo floats up and gives off a brilliant glow, as if he is a light bulb.

====''Mario Party 9''====
[[File:MP9 King Boo's Puzzle Attack 1.png|thumb|left|King Boo in his boss minigame in ''Mario Party 9'', King Boo's Puzzle Attack]]
King Boo appears as the stage boss of the board [[Boo's Horror Castle]] in ''[[Mario Party 9]]''. He is fought in the minigame, [[King Boo's Puzzle Attack]], where the competitors line up power-ups in lines of three or more to deal damage to him. Once his health reaches halfway, he throws Boos onto the field which can stun the player's cursors, making them unable to move until they shake the Boo off. What is unique about his boss battle is that if a player gets the Final Attack, they get ten points instead of the usual three, likely because the players can easily accumulate points up to fifty. In the [[Bowser's Block Battle|final fight]] against Bowser, King Boo can also appear to hinder the players' progress. If Bowser throws the die with all the stage bosses' faces on it and King Boo's face appears on top, King Boo materializes above the stage. Then, he summons five Boos that move in a counterclockwise direction while moving outwards. When the Boos reach the boundaries of the stage, King Boo summons another five Boos, except this time they move clockwise. After that, King Boo disappears from the battle unless his face appears on the top of the die again.

Like most other characters in the game, King Boo has a constellation that can be returned to the sky; it is called the Ghost Major. It is located in the farthest left portion of the sky, near [[King Bob-omb]]'s constellation and right next to Boo's constellation. Like all constellations, it can be bought for fifty Minigame Points. Also, in the [[Mario Party 9#Museum|Museum]]'s Sound Test, there are two voice sounds with the name "King Boo's Entrance"; one is of King Boo and the other is actually of Boo.
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====''Mario Party 10''====
[[File:King Boo's Tricky Tiles MP10.png|thumb|King Boo in his boss minigame in ''Mario Party 10'', King Boo's Tricky Tiles]]
King Boo in ''[[Mario Party 10]]'' is a boss in the minigame [[King Boo's Tricky Tiles]]. In order to defeat him, the player must remember which platforms are false, and then run around until they can jump on a light switch (one is worth 3 points, and another worth 1 point). Like other bosses, King Boo gets angered after the players deplete his health halfway. The technique that King Boo uses is that he swaps Boos with platforms and he blocks the camera, so the player can't see the platforms very well and remember which ones are false. He can also be seen on the [[Luigi Board]], which appears in the game's amiibo Party mode.

====''Mario Party: Star Rush''====
King Boo returns as a boss in ''[[Mario Party: Star Rush]]'' in his minigame, [[King Boo's Light Smite]]. In order to defeat him, players have to use [[Light Box]]es which they need to carry over rotating platforms while evading [[Peepa]]s. Once he loses half his health bar, the rotating platforms start moving faster and more Peepas appear, making it more difficult to reach the other side.
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====''Mario Party Superstars''====
King Boo appears in ''[[Mario Party Superstars]]'' on [[Horror Land]], replacing the [[Big Boo (character)|Big Boo]] found on the original board.<ref>{{cite|author=Nintendo|date=September 23, 2021|url=www.youtube.com/watch?v=dG9fAtmYdlM|title=Nintendo Direct - 9.23.2021|publisher=YouTube|accessdate=September 23, 2021}}</ref> He summons Boo lackeys to steal coins (for free) or Stars (for 150 coins) from all opponents who have any. As with the Big Boo in the original, he can only be encountered at night and only through a path that requires a [[Skeleton Key]].
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===''Mario & Sonic'' series===
====''Mario & Sonic at the Olympic Winter Games''====
[[File:King_Boo_-_Winter_Games.jpg|thumb|upright=0.85|left|[[Mario]] races against King Boo in the Wii version of ''Mario & Sonic at the Olympic Winter Games''.]]
In the [[Wii]] [[Mario & Sonic at the Olympic Winter Games (Wii)|version]] of ''Mario & Sonic at the Olympic Winter Games'', King Boo appears as the first and sixth (in Individual Festival mode only) rival. King Boo races the player in the [[Alpine Skiing Downhill]] event in both Individual and Group Festival modes but he only races the player in Giant Slalom in the Individual Festival mode, making him the only rival that can potentially be faced more than once. King Boo has no skis so he goes down the hill smoothly. If the player loses to him, the guide (either [[Cream (character)|Cream]] or [[Toad]]) says that it is unfair because King Boo has no skis.
 
[[File:KingBoo MASATOWG.png|thumb|King Boo as he appears in the DS version of ''Mario & Sonic at the Olympic Winter Games'']]
In the Adventure Tours mode in the [[Nintendo DS]] [[Mario & Sonic at the Olympic Winter Games (Nintendo DS)|version]], King Boo is the mid-boss of [[Polastraits]]. When the challenger approaches him, King Boo tells Mario/Sonic that he must race someone afraid of him. He selects Luigi and they must race in Giant Slalom. In this version, King Boo is transparent and the player can ski through him. He also appears slightly larger than in his other appearances.
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====''Mario & Sonic at the London 2012 Olympic Games''====
[[File:M&S 2012 The Ghostly Tower.png|thumb|left|200px|King Boo in [[The Ghostly Tower]]]]
In the Wii version of ''[[Mario & Sonic at the London 2012 Olympic Games (Wii)|Mario & Sonic at the London 2012 Olympic Games]]'', King Boo is one of the rival characters who can be found in the London Party mode, and when he is encountered, he challenges the player to the [[Dream Sprint]] event, with stickers being offered as a reward for beating him.

In the Nintendo 3DS [[Mario & Sonic at the London 2012 Olympic Games (Nintendo 3DS)|version]], King Boo appears in the Story Mode, where he helps guard the [[Phantasmal Fog]] at the [[Tower of London]], and teams up with a Boo to challenge [[Sonic]] and [[Tails]] in [[Badminton (Doubles)]]. When defeated, he and the Boo flee, and King Boo later appears at the opening ceremony for the games. A [[List of badges in Mario & Sonic at the London 2012 Olympic Games (Nintendo 3DS)|badge]] of King Boo can also be obtained from the badge machine.
 
King Boo is one of the three characters who appear as rivals in ''Mario & Sonic at the London 2012 Olympic Games'' but do not appear as playable characters in any version of ''Mario & Sonic at the Rio 2016 Olympic Games''. The other two are Boo and [[Magikoopa]].
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====''Mario & Sonic at the Sochi 2014 Olympic Winter Games''====
King Boo appears in ''[[Mario & Sonic at the Sochi 2014 Olympic Winter Games]]'' as a rival in the [[Legends Showdown]] mode. He appears in Area 4 and challenges the player in [[Short Track Speed Skating 1000m]].

===''Mario Golf: World Tour''===
[[File:King Boo golf cameo.jpg|thumb|King Boo in ''Mario Golf: World Tour'']]
King Boo appears in ''[[Mario Golf: World Tour]]'' on Hole 4 of [[Bowser's Castle (golf course)|Bowser's Castle]]. He is floating in the background alongside other [[Boo]]s, and he is also much larger than in other games. His name can also appear on the tournament scoreboard.

===''Super Smash Bros.'' series===
There are a few items of King Boo in the [[Super Smash Bros. (series)|''Super Smash Bros.'' series]]. In ''[[Super Smash Bros. for Nintendo 3DS]]'', there is a [[Trophy (Super Smash Bros. series)|trophy]] of King Boo. In ''[[Super Smash Bros. Ultimate]]'', King appears in his ''Luigi's Mansion: Dark Moon'' design as an Advanced-class Neutral-type primary [[Spirit (Super Smash Bros. Ultimate)|spirit]], which is enhanced from the Boo spirit after it has reached level 99. When equipped, the spirit grants the fighter slower fall speed after jumping and has 3 support slots. King Boo is listed as the 49th spirit, though he was listed as the 121st spirit alongside the rest of the spirits from the ''Luigi's Mansion'' series in version 1.0.0.<ref>{{cite|author=BeardBear|date=December 6, 2018|url=youtu.be/CiK68gO5XQM?t=336|timestamp=05:36|language=en|title=Super Smash Bros. Ultimate - All 1297 Spirits|publisher=YouTube|accessdate=December 23, 2018}}</ref>

===''Puzzle & Dragons: Super Mario Bros. Edition''===
King Boo appears as a boss and enemy in ''[[Puzzle & Dragons: Super Mario Bros. Edition]]'', mostly appearing at the Ghost House courses. His main attribute is Dark, while his sub-attribute is Light. As an ally, King Boo's skill can heal 1000 HP, and change all Heart Orbs into Dark Orbs. His Awoken Skill raises the amount of time that the player has to move Orbs around.

As an enemy, King Boo is capable of decreasing the player's maximum time to move Orbs around. Also, King Boo is treated as a generic enemy, so he can still appear as an enemy, regardless of whether or not the player has King Boo in their party. Big Boo can be transformed into a King Boo with six [[Boo Mushroom]]s as a Transformation Item, making it possible to create multiple King Boos on the player's team.

When King Boo attacks, a bunch of [[Boo]]s attack with him.

King Boo's best stats are his ATK and RCV, while his HP is at an average level.

===''Mario & Luigi: Paper Jam''===
{{quote|Look at this little scrap. Friend of yours, is he? Well, if you like your friend, you better stop attacking me! Now, don't go thinking it's OK to attack my little minion either. Who knows what could happen if he dropped your little friend there... You got that?|King Boo|Mario & Luigi: Paper Jam}}
[[File:M&L Paper Jam King Boo.png|thumb|left|250px|King Boo, attempting to fool Mario and Luigi by disguising himself as Paper Mario, in ''Mario & Luigi: Paper Jam'']]

King Boo appears as a boss in ''[[Mario & Luigi: Paper Jam]]''. King Boo has a papercraft version of himself piloted by [[Morton Koopa Jr.|Morton]] and [[Lemmy Koopa|Lemmy]], which is fought in [[Bowser's Castle]]. The Mario Bros. use Papercraft Yoshi to fight it.

The real King Boo is encountered and fought in [[Gloomy Woods]] after the trio separate, leading to him kidnapping Mario and [[Paper Mario (character)|Paper Mario]]; leaving Luigi alone to find them, like in the ''Luigi's Mansion'' series. After finding [[Mario]], he and Luigi begin to look for Paper Mario. They eventually find King Boo instead, disguised as Paper Mario. When they group together, King Boo reverts back to normal and laughs at the Bros. for a second, before re-transforming; Mario and Luigi then turn around, and are unaware of King Boo's presence. When they turn around again, King Boo reveals himself again, but is caught by the duo. In an attempt to fool them, he immediately reverts back to Paper Mario, and tries to convince the Bros. that he is the real Paper Mario, but fails. King Boo then loses control of his transformation powers, as he quickly transforms into Paper Peach and then Paper Bowser, before finally gaining control and giving up; reverting back to his true form, causing the battle to commence.

King Boo attacks by spitting blue fireballs at either Mario or Luigi before inhaling them; making them need to avoid the fireballs twice, and splitting into five copies before floating slowly towards the trio, turning invisible as he gets near; which the trio must counter using their hammers around 2 seconds after a copy turns invisible. During the battle, King Boo calls a [[Paper Boo]] holding the real Paper Mario onto the battlefield; threatening to harm Paper Mario if the bros attack either himself or the Paper Boo. In order to save Paper Mario, Mario and Luigi must defeat the minion holding onto Paper Mario, causing it to drop him. If King Boo is attacked while the Paper Boo is on the battlefield, he deals damage to Paper Mario. After a few turns, another Paper Boo can grab Paper Mario again, taking him out of the battle (which gets rid of Paper Mario's copies) temporarily. Finally, King Boo also has a chase attack where he grows bigger before attempting to shoot a giant blue fireball at the trio; which Mario and Luigi have to counter by throwing Paper Mario's boomerang form into King Boo's mouth while it is open. Once defeated, Paper Mario is reunited with the duo and the group continues to [[Mount Brrr]]. 

Due to his crown, King Boo is immune to the brothers' [[Jump]] attack (but he can be hit by [[Hammer]] attacks, unlike Paper Boos) and certain [[Bros. Attack]]s, such as the [[Rocket Blast]] and [[Mega Thwonk]]'s jumping attacks (only in the [[Arcade (Mario & Luigi: Paper Jam)|arcade]]). Attacking King Boo using attacks from above results in the Bro. taking 1 damage as if they were jumping on a spiked enemy. The [[Dropchopper]], however, can circumvent this as it can be aimed towards King Boo's forehead instead of his crown and can then damage him.

The splitting attack used by King Boo is a reference to (if not a direct copy of) the [[Dark Star]]'s splitting attack in ''[[Mario & Luigi: Bowser's Inside Story]]'', except King Boo takes damage if countered unlike the Dark Star's version due to it being invincible. As well, if the Mario Bros. continue to attack King Boo without freeing Paper Mario, his slapping Paper Mario may be an allusion to [[Lady Bow]] and her slap attacks<ref>{{cite|author=Gaming Reinvented|date=January 8, 2016|url=www.youtube.com/watch?v=74SYLTwZ2Aw|title=Mario & Luigi Paper Jam; King Boo Kills Paper Mario!|publisher=YouTube|accessdate=February 7, 2024}}</ref>. Also, King Boo's voice clips from ''[[Mario Kart Wii]]'' are reused.
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===''Mario + Rabbids Kingdom Battle''===
King Boo makes a cameo appearance in ''[[Mario + Rabbids Kingdom Battle]]'' in [[Spooky Trails]], where an image of him can be found on the ground in the area where the gramophone is found.

===''Mario Tennis Aces''===
King Boo appears in ''[[Mario Tennis Aces]]'' as part of the Boo Hunt Co-op Challenge available from version 2.0.0. When Frenzy Time is active, King Boo appears and hovers around the court. Players can continuously hit tennis balls at him to earn more coins. He disappears once either his health bar or the Frenzy bar is depleted. In this appearance, he does not use any of his normal voice clips, instead using those of a regular Boo.

===''Dr. Mario World''===
[[File:DMW-Dr. King Boo Solo Art.png|thumb|100px|Dr. King Boo in ''Dr. Mario World'']]
King Boo appears in ''[[Dr. Mario World]]'' as assistants, added on November 14, 2019.<ref>{{cite|author=DrMarioWorld_EN|date=November 14, 2019|url=x.com/Drmarioworld_EN/status/1195137397639536641|title=Blue: "Tiers 6 and 7 were added to versus mode! Apparently you can add a new assistant, King Boo, from the battle boxes for tier 7. You need 2,600 battle points to reach tier 7, but I know you can do it!" #DrMarioWorld|publisher=X|accessdate=September 28, 2020}}</ref> He is a battle box-exclusive assistant, only obtainable from battle boxes for tier 7 or above in versus mode. In versus mode, he has a chance of sending 2 extra rows of viruses to the opponent if the attack lands. In stage mode, he grants a chance of 5 extra capsules being added when 5 capsules are remaining, which will have a chance to activate again if the condition is met again but didn't activate earlier. However, it won't activate for the rest of the stage if this effect has successfully activated. 

He also appears as a doctor named '''Dr. King Boo''', available September 28th, 2020. Like [[Dry Bowser|Dr. Dry Bowser]], he cannot be obtained in staffing and must be obtained through either in-app purchases or unlocking him through rewards such as in [[World 20]]'s Special Stage or through certain referrals. His skill is to eliminate an amount of viruses even those that would normally take multiple hits to clear such as [[floatie virus]]es. In stage mode, the amount is 5 viruses (4 prior to version 2.2.0), while in versus mode, the amount differs based on level, where it is 4 at level 1 with three extra viruses per level, up to 16 at the maximum level of level 5. In stage mode, if there are no more viruses while this skill is activated, it will eliminate one random object that can be eliminated instead, excluding capsules. 
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===''The Super Mario Bros. Movie''===
King Boo has a minor appearance in ''[[The Super Mario Bros. Movie]]'' at Bowser and Peach's wedding with his ''Super Mario'' design. He is seen sitting a few rows behind [[King Bob-omb]]. He does not have any role in the climax nor does he speak. He disappears once Peach, Mario, and [[Donkey Kong]] crash the wedding. Compared to his usual design, his face is smaller and is more expressive, taking up less space on his overall body and somewhat resembling that of the ''[[Super Mario Sunshine]]'' [[Big Boo (character)|King Boo]]. He is also the only Boo that appears in the movie.

==General information==
===Physical appearance===
{{multiple image
|align=right
|direction=horizontal
|footer=King Boo's ''Super Mario'' design (left) and his ''Luigi's Mansion'' design (right)
|image1=King Boo Artwork MSS.png
|width1=175
|image2=LM3 King Boo artwork.png
|width2=166
}}
King Boo has had two distinct appearances throughout his video game history. In most ''Super Mario'' games since ''[[Mario Kart: Double Dash!!]]'', King Boo resembles a normal Boo with a golden, five-pointed crown, though he is much larger. With this design, the crown has a blue jewel on the front and four red jewels around the sides in every game except ''Mario Super Sluggers'', where the colors are reversed. Like other Boos, King Boo is generally shown with an open, wide grin; however, when looked at, he closes his mouth and bashfully hides his face with his hands. In certain games like ''[[Mario Party 9]]'', King Boo's emotions are denoted by an aura surrounding him: when happy, he glows with a blue aura, and when angry, he glows with a red aura. Sometimes he also has steam coming out of him to display his anger. In ''[[Dr. Mario World]]'', he has a doctor's mirror on his crown and he carries a medicine box by strap. His gold variant in ''[[Mario Kart Tour]]'' is based on this design, and has an entirely golden body similar to a [[Gold Boo]], though his teeth and tongue are golden as well. His crown is silver and all five jewels are blue.

King Boo's other design was first used for his debut appearance in ''[[Luigi's Mansion]]'', and has since been reused in the subsequent ''[[Luigi's Mansion (series)|Luigi's Mansion]]'' games. This original design gave King Boo dark red eyes, a blue tongue, two vampire-like fangs, a greenish complexion, and a ruby in a gold, round-edged crown. He is also roughly the same size as other Boos. Starting with ''[[Luigi's Mansion: Dark Moon]]'', this design was slightly modified, giving him a full row of four teeth and a larger size typical of King Boo's modern design. Other differences include a larger shadow surrounding his eyes, a dark indigo mouth and tongue, and his crown containing a purple jewel and pointed edges. His [[:File:King Boo Artwork - Luigi's Mansion Dark Moon.png|artwork]] depicts him with purple eyes instead of red, its color in-game, and without his crown's pointed edges. He has also lost his original green tint, now being more of a lavender color. In ''[[Luigi's Mansion 3]]'', King Boo shows more expression, scowling at Luigi when first being found by him and appearing visibly disappointed when captured in the game's credits. He also has purple eyes in-game. His speech icon also uses a green shading reminiscent of his initial appearance, while his portraits show him with a purple crown. In ''Mario Kart Tour'', King Boo's ''Luigi's Mansion'' variant uses this design, although his tongue is more purple than indigo.

===Personality===
[[File:3DS LMansion 2 illu02 E3.png|thumb|200px|King Boo shows a particular disdain for Luigi in the ''Luigi's Mansion'' series.]]
King Boo is a sadistic villain who enjoys scaring and tricking his enemies by creating illusions and then overpowering and trapping them. King Boo often taunts Luigi and E. Gadd. In ''Luigi's Mansion 3'', for instance, King Boo mocks Mario and Luigi's Italian accent by saying, "It's-a me, King Boo!", and in ''Luigi's Mansion: Dark Moon'' he pretends to confuse between Luigi and Baby Luigi. In ''[[Mario & Sonic at the Olympic Winter Games (Nintendo DS)|Mario & Sonic at the Olympic Winter Games]]'', he insists on racing against Luigi, knowing how afraid he is of ghosts. King Boo also holds grudges, referring to his prior defeat in ''Luigi's Mansion'' sarcastically as "Good times" and he has stated that he is "sick to double death" of Luigi. In frustration, he recites the noise of the [[Poltergust 3000]], which he refers as a "disgusting machine", capturing him.

King Boo admires paintings and other decorations, such as making lengthy comments on how good Mario is as a painting; E. Gadd also comments that King Boo has decorated [[Treacherous Mansion]] to be scarier. He also desires to trap Luigi and E. Gadd through similar means.

King Boo boasts frequently about himself. He always proclaims his success in escaping, and he claims he fears nothing except the Poltergust 3000, although in ''[[Super Mario 64 DS]]'' he admits that Wario's face scares him. In the ''Mario and Sonic'' series, ''[[Mario & Sonic at the Olympic Winter Games (Wii)|Mario & Sonic at the Olympic Winter Games]]'', he claims that he is unbeatable at the [[Alpine Skiing]] event. Despite his power, he still covers his face in fear when looked at, much like a normal Boo. King Boo has a distinct cackle, which is quite lower in pitch than other Boos.

===Powers and abilities===
In ''[[Luigi's Mansion]]'', King Boo's power increases when he is in the presence of other Boos. For example, King Boo can blow Luigi to the Foyer when enough Boos are in the mansion. King Boo can also materialize things, including pulling a mansion out of the ghost dimension, creating replicas of some of Mario's enemies, other Boos, dimensions to battle in, bubbles, and blue fire (which he spits out of his mouth). King Boo can regenerate from his crown in ''[[Super Princess Peach]]''

In ''[[Luigi's Mansion: Dark Moon]]'', King Boo can open [[paranormal portal]]s to the ghost dimension, create traps such as sand patches, electrify terrain to shock Luigi, grow to large sizes, and teach Boos how to create [[Spirit Ball]]s. His new crown can also shoot an ectoplasmic laser that can shatter the [[Dark Moon]] or trap [[Toad (species)|Toads]] within paintings. King Boo can create illusions, hence his title "The Master of Illusions." In this game, similar to ''Luigi's Mansion'', his power is stronger when there are other Boos in the vicinity. 

[[File:LM3 King Boo Final Battle.png|thumb|left|King Boo can create clones and shoot fireballs from his crown in the final battle of ''Luigi's Mansion 3'']]
In ''Luigi's Mansion 3'', King Boo summons magical paintings to trap people and, to a certain extent, objects inside. He can enlarge portraits in order to capture people, as an extension of his paranormal portals. He does not need the presence of other Boos to grow stronger in this game.

King Boo has a high power stat in many of his spin-off appearances. This is most noticeable in the [[Mario Baseball (series)|''Mario Baseball'' series]], where he is able to hit home runs easily. His great strength is also shown in ''Luigi's Mansion: Dark Moon'', as he summons and makes spike balls fall down simply by slamming the platform.  

In ''[[Mario & Luigi: Paper Jam]]'', King Boo shapeshifts to trick Mario and Luigi by posing as Paper Mario, and he later briefly transforms into Paper Peach and Paper Bowser. He can also spit blue fireballs.

===Relationships===
====Enemies====
King Boo and Luigi are arch-nemeses in the ''Luigi's Mansion'' games. King Boo's motivation for trying to imprison Mario and Luigi is for revenge that both brothers have posed trouble against him in the past. King Boo additionally dislikes Professor E. Gadd for his ghost-capturing hobby, involving capturing his Boos. King Boo additionally states that the only thing that scares him is E. Gadd's invention, the Poltergust 3000.  In ''[[Mario Superstar Baseball]]'', King Boo has negative chemistry with Luigi and [[Baby Luigi]]; in ''[[Mario Super Sluggers]]'', he has bad chemistry with Mario, [[Princess Peach]], [[Princess Daisy]], [[Baby Mario]], [[Baby Peach]], [[Baby Daisy]], and [[Yoshi]]. King Boo also traps Toads in ''Luigi's Mansion: Dark Moon'' and captures Princess Peach in ''Luigi's Mansion 3''.

Generally speaking, King Boo cares nothing for ghosts that are not Boos, considering them expendable to advance his grand schemes such as in ''Luigi's Mansion: Dark Moon'' where he caused friendly ghosts to turn hostile so he can try to take over Mushroom Kingdom. Even Hellen Gravely, who has great admiration for King Boo, is seen by him as nothing more than a tool for his plans, and he is quick to dismiss her as useless once she fails to capture Luigi.

====Friends====
[[File:MP9 Bowser Block Battle 15.png|thumb|King Boo assists Bowser by summoning Boos in ''Mario Party 9''.]]
King Boo has been shown to work with Bowser on numerous occasions, including ''Super Mario 64 DS'', ''Mario Party 9'', and ''Super Princess Peach''. He also used a Bowser decoy and the two share a portrait after King Boo's defeat in ''Luigi's Mansion''. Despite this, the two share neutral chemistry in ''Mario Superstar Baseball'' and ''Mario Super Sluggers'', with King Boo appearing on [[Wario]]'s team rather than Bowser's. King Boo has also been paired up with [[Petey Piranha]] in ''Mario Kart: Double Dash!!'', with the two sharing chemistry in the ''Mario Baseball'' games. King Boo also has good chemistry with [[Wiggler]] and King K. Rool in ''Mario Super Sluggers''. ''[[Luigi's Mansion 3]]'' shows [[Hellen Gravely]] admiring King Boo, with her releasing him to impress and aid him in his plot for revenge against Luigi. However, her admiration is entirely one-sided as King Boo pays little consideration toward Hellen Gravely and is more interested in capturing Luigi and E. Gadd.

King Boo also relies on his Boo minions (even outright referring to them as his friends in ''Luigi's Mansion''), which cooperate to try to capture Luigi and his friends. In ''Luigi's Mansion'', he frees [[Boolossus]] from [[Professor Elvin Gadd|Professor E. Gadd]], and in ''[[Mario & Luigi: Paper Jam]]'', he threatens to hurt [[Paper Mario (character)|Paper Mario]] if the Mario Brothers hurt his [[Paper Boo]] minion. He has good [[chemistry]] with the playable Boo in the [[Mario Baseball (series)|''Mario Baseball'' series]]. In ''[[Mario Super Sluggers]]'', King Boo says that he finds little Boos cute. However, in the later ''Luigi's Mansion'' titles, he can be just as cruel to them as he is to his other ghost minions, showing no concern for them being sucked up by Luigi and even actively putting them in harm's way, as well as indirectly calling them useless in the latter game.

==Quotes==
{{main|List of King Boo quotes}}
*"''Aahh, I could just stare at my Mario painting for hours! It's true what they say about fine art...it takes utterly refined sensibilities to truly appreciate it! The way you plead for help, Mario... I find it so...satisfying. Perhaps that is merely because I remember how much trouble you've caused me in the past. ... Seriously, though, who would actually believe that mansions get given away in contests?! Talk about stupid! What do they feed you Mario brothers anyway...gullible soup? Your brother came all this way just to get turned into a painting... It's just terrific. However... This Mario painting looks lonely... I must have a Luigi painting as well! Then my gallery will truly be complete! Bleah HA HA! I am not afraid of you, fool! I fear only that infernal Poltergust 3000 you carry on your back! Stupid machine! But I am a KING among Boos! I swear it... I shall fear no mere house-cleaning device!! I must say...I despise the way you SHWEEERRPP-SHLOOOOP-WHOOORPP-SHLEEEOOORG-vacuumed up all my friends! Don't imagine that I'll flee... I'll fight you like a true Boo! Now join your brother... ...inside the painting!''" - ''[[Luigi's Mansion]]''
*"''Bah! You don't have enough coins! King Boo says boo to you! And good-bye!!!''" - ''[[Mario Party 8]]''
*"''Say WHAT? You want ME to help YOOOOOU?''" - ''[[Mario Super Sluggers]]''
*"''Heh heh heh! I saw that Alpine Downhill event of yours yesterday! Looks like you need to take a lesson in speed from ME! And that lesson starts today! I challenge you to an Alpine Downhill match! Hee hee hee!''" - ''[[Mario & Sonic at the Olympic Winter Games (Wii)|Mario & Sonic at the Olympic Winter Games]]'' (Wii)
*"''...Hmm? One-two-three-four-five-six-sev-- WAIT! There should be seven! Who's missing!? [...] Luigi! What are you doing over there?! UGH! That's it! I'm sick to double death of you! You want to fight me? FINE! Let's go, Luigi! This is the end for you, once and for all! HERE I COME!''" - ''[[Luigi's Mansion 3]]''

==Voice samples==
{{media table
|file1=King Boo's laugh 2004.oga
|title1=''[[Super Mario 64 DS]]''
|description1=King Boo's laughter
}}

==Profiles and statistics==
{{main|List of King Boo profiles and statistics}}

==List of appearances==
{{appearances list
|title1=''[[Luigi's Mansion]]''
|role1=Main antagonist, final boss
|release1=2001
|format1=[[Nintendo GameCube]]
|title2=''[[Mario Kart: Double Dash!!]]''
|role2=Unlockable playable character
|release2=2003
|format2=Nintendo GameCube
|title3=''[[Super Mario 64 DS]]''
|role3=Boss
|release3=2004
|format3=[[Nintendo DS]]
|title4=''[[Mario Superstar Baseball]]''
|role4=Playable character
|release4=2005
|format4=Nintendo GameCube
|title5=''[[Super Princess Peach]]''
|role5=Boss
|release5=2005
|format5=Nintendo DS
|title6=''[[Mario Kart DS]]''
|role6=Boss in Mission Mode
|release6=2005
|format6=Nintendo DS
|title7=''[[Mario Party 8]]''
|role7=Non-playable character
|release7=2007
|format7=[[Wii]]
|title8=''[[Mario Kart Arcade GP 2]]''
|role8=Cameo
|release8=2007
|format8=Arcade
|title9=''[[Mario Kart Wii]]''
|role9=Unlockable playable character
|release9=2008
|format9=Wii
|title10=''[[Mario Super Sluggers]]''
|role10=Playable character
|release10=2008
|format10=Wii
|title11=''[[Mario & Sonic at the Olympic Winter Games]]''
|role11=Rival
|release11=2009
|format11=Wii, Nintendo DS
|title12=''[[Mario & Sonic at the London 2012 Olympic Games]]''
|role12=Rival
|release12=2011, 2012
|format12=Wii, [[Nintendo 3DS]]
|title13=''[[Mario Party 9]]''
|role13=Boss
|release13=2012
|format13=Wii
|title14=''[[Luigi's Mansion: Dark Moon]]''
|role14=Main antagonist, final boss
|release14=2013
|format14=Nintendo 3DS
|title15=''[[New Super Luigi U]]''
|role15=Cameo
|release15=2013
|format15=[[Wii U]]
|title16=''[[Mario & Sonic at the Sochi 2014 Olympic Winter Games]]''
|role16=Rival
|release16=2013
|format16=Wii U
|title17=''[[Mario Golf: World Tour]]''
|role17=Non-playable character/cameo
|release17=2014
|format17=Nintendo 3DS
|title18=''[[Super Smash Bros. for Nintendo 3DS]]''
|role18=[[Trophy (Super Smash Bros. series)|Trophy]]
|release18=2014
|format18=Nintendo 3DS
|title19=''[[Mario Party 10]]''
|role19=Boss
|release19=2015
|format19=Wii U
|title20=''[[Puzzle & Dragons: Super Mario Bros. Edition]]''
|role20=Boss
|release20=2015
|format20=Nintendo 3DS
|title21=''[[Mario & Luigi: Paper Jam]]''
|role21=Boss
|release21=2015
|format21=Nintendo 3DS
|title22=''[[Luigi's Mansion Arcade]]''
|role22=Main antagonist, final boss
|release22=2015
|format22=Arcade
|title23=''[[Mario Party: Star Rush]]''
|role23=Boss
|release23=2016
|format23=Nintendo 3DS
|title24=''[[Mario Kart 8 Deluxe]]''
|role24=Playable character
|release24=2017
|format24=[[Nintendo Switch]]
|title25=''[[Mario Kart Arcade GP DX]]''
|role25=Playable character <small>(during a limited-time event)</small><br>Unlockable playable character <small>(for permanent use, through a limited-time event)</small>
|release25=2017
|format25=Arcade
|title26=''[[Mario + Rabbids Kingdom Battle]]''
|role26=Cameo
|release26=2017
|format26=Nintendo Switch
|title27=''[[Mario Tennis Aces]]'' (version 2.0.0)
|role27=Boss
|release27=2018
|format27=Nintendo Switch
|title28=''[[Luigi's Mansion (Nintendo 3DS)|Luigi's Mansion]]''
|role28=Main antagonist, final boss
|release28=2018
|format28=Nintendo 3DS
|title29=''[[Super Smash Bros. Ultimate]]''
|role29=[[Spirit (Super Smash Bros. Ultimate)|Spirit]]
|release29=2018
|format29=Nintendo Switch
|title30=''[[New Super Mario Bros. U Deluxe]]''
|role30=Cameo
|release30=2019
|format30=Nintendo Switch
|title31=''[[Dr. Mario World]]''
|role31=Assistant (update)
|release31=2019
|format31=iOS / Android
|title32=''[[Mario Kart Tour]]''
|role32=Unlockable playable character (update)
|release32=2019
|format32=iOS / Android
|title33=''[[Tetris 99]]''
|role33=Cameo in TETRIS x Luigi's Mansion 3 Event
|release33=2019
|format33=Nintendo Switch
|title34=''[[Luigi's Mansion 3]]''
|role34=Main antagonist, final boss
|release34=2019
|format34=Nintendo Switch
|title35=''[[Mario Party Superstars]]''
|role35=Non-playable character
|release35=2021
|format35=Nintendo Switch
|title36=''[[Mario Kart Live: Home Circuit]]'' (version 2.0.0)
|role36=Non-playable character
|release36=2021
|format36=Nintendo Switch
|title37=''[[Super Mario Bros. Wonder]]''
|role37=Enemy
|release37=2023
|format37=Nintendo Switch
}}

==Gallery==
{{main-gallery|King Boo}}
<gallery>
LuigisMansionKingBooModel.png|''[[Luigi's Mansion]]''
King Boo MKDD Model.png|''[[Mario Kart: Double Dash!!]]''
SPP-King Boo Sprite.png|''[[Super Princess Peach]]''
MP9 King Boo Bust.png|''[[Mario Party 9]]''
PDSMBE-KingBoo-TeamImage.png|''[[Puzzle & Dragons: Super Mario Bros. Edition]]''
MKT Artwork KingBooLuigisMansion.png|''[[Mario Kart Tour]]''
</gallery>

==Names in other languages==
<!--To edit this table, access the "List of King Boo names in other languages" page and go to the "King Boo" section.-->
{{main|List of King Boo names in other languages}}
{{:List of King Boo names in other languages|transcludesection=King Boo}}

==Trivia==
*When King Boo says, "''I will not give up my favorite decoration. I like Mario just where he is,''" he references a quote from ''{{wp|Return of the Jedi|Star Wars Episode VI: Return of the Jedi}}'', when {{wp|Jabba the Hutt}} says, "''I will not give up my favorite decoration. I like {{wp|Han Solo|Captain Solo}} where he is.''"
*King Boo's laugh originating from ''Luigi's Mansion'' is actually a pitched-up version of a stock laughing sound effect.<ref>{{cite|url=soundeffects.fandom.com/wiki/Sound_Ideas,_CARTOON,_LAUGHTER_-_LOW,_THROATY_LAUGH,_HUMAN_01|title=Sound Ideas, CARTOON, LAUGHTER - LOW, THROATY LAUGH, HUMAN 01|publisher=Soundeffects Wiki|accessdate=October 10, 2022}}.</ref> A pitched-down version of the same effect was previously used for [[Bleak]].

==References==
<references/>

{{navboxes|
{{Boos}}
{{LM}}
{{MGTT}}
{{MKDD}}
{{SM64}}
{{MSB}}
{{SPP}}
{{MKDS}}
{{MP8}}
{{MKAGP2}}
{{MKW}}
{{Mario Super Sluggers}}
{{M&SATOWG}}
{{M&SATLOG}}
{{MP9}}
{{LMDM}}
{{M&SATSOWG}}
{{MP10}}
{{M&LPJ}}
{{MPSR}}
{{MK8}}
{{MKAGPDX}}
{{MTA}}
{{DMW}}
{{MKT}}
{{LM3}}
{{MPS}}
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{{SMBW}}
}}
[[Category:Boos]]
[[Category:Shapeshifters]]
[[Category:Portrait ghosts]]
[[Category:Kings|Boo]]
[[Category:Final bosses]]
[[Category:Playable characters]]
[[Category:Dr. Mario World]]
[[Category:LEGO Super Mario characters]]
[[Category:Mario & Luigi: Paper Jam bosses]]
[[Category:Mario & Luigi: Paper Jam characters]]
[[Category:Mario & Sonic at the London 2012 Olympic Games characters]]
[[Category:Mario & Sonic at the Olympic Winter Games characters]]
[[Category:Mario & Sonic at the Sochi 2014 Olympic Winter Games characters]]
[[Category:Mario Golf: World Tour characters]]
[[Category:Mario Kart 8 Deluxe characters]]
[[Category:Mario Kart DS bosses]]
[[Category:Mario Kart Tour characters]]
[[Category:Mario Kart Wii characters]]
[[Category:Mario Kart: Double Dash!! characters]]
[[Category:Mario Party 8 characters]]
[[Category:Mario Party 9 bosses]]
[[Category:Mario Party 10 bosses]]
[[Category:Mario Party: Star Rush bosses]]
[[Category:Mario Party Superstars characters]]
[[Category:Mario Superstar Baseball characters]]
[[Category:Mario Super Sluggers playable characters]]
[[Category:Super Mario Bros. Wonder enemies]]
[[Category:Super Mario 64 bosses]]
[[Category:Super Princess Peach bosses]]
[[Category:Super Smash Bros. for Nintendo 3DS trophies]]
[[Category:Super Smash Bros. Ultimate spirits]]
[[Category:The Super Mario Bros. Movie characters]]
[[de:König Buu Huu]]
[[it:Re Boo]]