Uub

Uub is an Human, Being the positive reincarnation of the completely evil Kid Buu, his name is Buu backwards.

Dragon Ball Z
At the age of ten, Uub is seen at the World Martial Arts Tournament, which takes place ten years after the defeat of Kid Buu. It is revealed that Uub is actually the reincarnated form of Kid Buu. He is trained by Goku and becomes a Z fighter. entering the World Tournament; his plan was to attempt to win the prize money of 10,000,000 zeni in order to feed his poor village.

Uub is set to challenge Goku in the first round. He becomes very nervous. When fighting Goku, he regains his confidence, after Goku purposely verbally attacks him, insulting his parents. Uub's power increases to a point of being able to hurt Goku. After Goku and Uub's match, Goku apologizes, then offers to train Uub. At first Uub is worried about the prize money, but Goku states he will have Mr. Satan give Uub all the money he needs. They both then head to Uub's village to train.