Morton Koopa Jr.
Morton Koopa Jr. is one of Bowser's eight children and is the sixth oldest Koopaling. Although he has a large build, Morton doesn't appear to be as powerful as some of his other large brothers, like Ludwig or Roy. This may just be due to the fact that he is one of the younger Koopalings, and needs to grow some more.
Unlike his siblings, many of Morton's features are unique, and are not shared traits. He is the only Koopaling to have brown skin, whereas the others all have orange skin. Morton is also the only one of his siblings to have a unique shell color. While his siblings have either green or pink shells, only Morton has a gray one. Another unique feature of Morton's is the large, star-shaped birthmark on the left side of his face.
History
Morton's first appearance was in Super Mario Bros. 3 where he, along with his siblings (minus Bowser Jr.) aided their father in an attempt to take over the Mushroom World. Morton usurped the sultan of Desert Land and took over, but in the end he was defeated by Mario. Morton appeared again in Super Mario World helping his family in an attempt to take over Dinosaur Land, here he had taken over Donut Plains and attacked Mario by climbing the walls and ceiling of his room and dropping down. Morton was defeated but still helped his family in causing chaos in Hotel Mario, Yoshi's Safari and Mario is Missing, but after all these adventures Morton along with the other six original Koopalings disappeared. Morton and his bros. and sis reappeared in Mario & Luigi: Superstar Saga were they guarded Bowser's Castle, here Morton learned a new attack, sending shockwaves. Despite this new attack Morton ended up being beaten and has once again disappeared.
Some unused sprites of Morton were found in Super Princess Peach which has spread speculation that the Koopalings were going to appear in it. 1
Cartoons
In The Adventures of Super Mario Bros. 3 and Super Mario World cartoons he was renamed Big Mouth Koopa, ostensibly because he was more talk than action. Aptly, in the Super Mario World cartoon, he occasionally served as an announcer. There are a few physical differences between Morton and Big Mouth: Morton's shell is gray and in the Super Mario Bros. 3 cartoon, Big Mouth's is purple; Big Mouth has much larger eyes and purple eyelids; and the star-shaped birthmark on Morton's face is darker around the cheek, while it's just one solid color on Big Mouth. Big Mouth's rambles were given by Dan Hennessey.
Name Controversy
The fact that Morton's name ends in a "Jr." has made some fans wonder if Bowser's actual first name is "Morton" as well. This is not the case. This curious nominal suffix is merely a nod to Morton's namesake, just as the "von" in Ludwig Von Koopa is a nod to Beethoven. Any speculation into other possibilities of brown-skinned Morton being adopted into the yellow-skinned Koopa family, for example Jr. has no basis in Nintendo canon, as Nintendo has never opined on the issue, one way or the other. In fact, the editors of the magazine Nintendo Power once claimed that when they asked Bowser why Morton Koopa was called "Jr.", he responded by pelting them with Bob-ombs.
One possibility is that Morton is Bowser's middle name, and Morton Jr. goes by this to avoid confusion.
