Donkey Kong Jr.
Donkey Kong Jr. (sometimes shortened to DK Jr.) is the younger version of Donkey Kong. Interestingly, Donkey Kong Jr. is the star of the second Mario game ever. In arcade game Donkey Kong Jr., Donkey Kong Jr. must save his dad, Cranky Kong (the original DK), who has been imprisoned in a cage by Mario, who was tired of him constantly kidnapping Pauline. Donkey Kong Jr.'s quest was to swing across vines to find the keys and save his dad. However, Mario sent enemies out to attack DK Jr. The young ape could drop fruit on the enemies to defeat them. At the end of the game, DK Jr. saved his dad from Mario's cage.
Donkey Kong Jr. appeared as a playable character in Super Mario Kart. He is a heavyweight and as such has similar attributes to Bowser. His weapon of choice is the Banana, which he would litter the racetracks with. (His adult form would appear in Mario Kart 64).
Donkey Kong Jr. is also a playable character in Mario Tennis. Additionally, his adult form is also a playable character. (Similarly, Mario appears in his current state and as Baby Mario.)
Donkey Kong Junior has his own series of educational games for the NES and PC. He occasionally makes appearances in other games such as Donkey Kong '94 and the Game & Watch Gallery series. However, DK Jr. appears to have been replaced by Diddy and Dixie Kong. He has now been reduced to making minor cameos in games like Mario Kart: Double Dash!!. He also makes a cameo in the GBA version of Super Mario Bros. 3. One of the kings is turned into him. Or, at least, a look-alike ape.
Donket Kong Jr. will appear in Yoshi's Island DS, however with the name Baby Donkey Kong. It is also unknown if the baby is Donkey Kong or Cranky Kong. Instead of his white leotard Donkey Kong Jr. will be wearing a red bib with the letters D.K. on it.
