Buu is a creation of the evil wizard Bibidi, who sent to kill the Supreme Kais - the guardians of the universe. Buu killed all but one, but his great power was too much even for his creator to handle. Bibidi was forced to seal Buu in a cocoon, and without Buu, Bibidi was killed by the remaining Supreme Kai. This orb was hidden on the Earth and forgotten for many, many years.
Major Story Arcs
Unbeknownst to the Supreme Kai, Bibidi had a son Babidi. Babidi was just as evil and swore revenge on the Supreme Kai as well as universal domination. Babidi discovered Buu on Earth and gathered many evil fighters to his control. He gained control of Earth fighters Spopovich and Yamu and sent them to retrieve energy to restore Buu to full power and release him from his prison.
Seven years after Gohan killed Cell, another World Martial Arts Tournament was held. The Z-Fighters entered and were fine until Babidi's men attacked Gohan. Gohan was held frozen by the Supreme Kai so that the men could get his energy and leave with it. The Z-Fighters joined the Supreme Kai and followed them back to Babidi's space ship. The Z-Fighters, fought there way through the ship until Vegeta let himself be manipulated by Babidi. Goku and Vegeta battled, and with each blow Buu's orb absorbed more energy.
Buu is Awakened
After absorbing enough energy, Buu was finally released from his prison. Buu quickly killed Babidi's right hand man, Dabura, as if he was nothing. Gohan and the Supreme Kai then battled Buu but were not powerful enough to keep up with him. After Gohan apparently died and Supreme Kai was beaten, Vegeta ends up on the scene. Even with his new power, Vegeta couldn't damage Buu. In a final move, Vegeta sacrifices himself with one final attack. But even after giving it everything he had, Buu still managed to reform.
Goku then arrives on the scene where he powers up to his new transformation Super Saiyan 3. Goku was able to evenly match Buu's power in this new form, but wasn't trying to beat him. Goku was stalling so Trunks could get the Dragon Radar. After Trunks had gotten the Radar, Goku told him that if Buu waited he would have someone much more powerful to play with. Buu agreed but when Babidi ordered him to keep fighting Buu killed his master.
Goku then teaches Goten and Trunks how to fuse, but before they were ready the rushed in to use this new Fusion to fight Buu. The fusion was quickly defeated and returned for more training.
After Majin Buu kills Babidi he goes on a killing spree (turning people into chocolate/ other candies and eating them) and then uses his powers to create a house for himself. Eventualy the world champion, Hercule Satan, finds Buu and instead of trying to kill him, he befriends him. Buu accepts this act of kindness, and they become best friends. One day these hunters were going around and shot a puppy. Buu punishes the hunters and heals the puppy. He calls the puppy Bee. After this, Buu separated the good inside of him from the evil. The two halves clash. Evil Buu wins the battle and eats the good Buu.
Good Separated From Evil
After eating the good Buu, Evil Buu changes into Super Buu. Super Buu has only two things on his mind: murder and candy. He ends up transforming countless cities into candy and devours them. Super Buu soon finds the lookout, where he absorbs everyone but Piccolo who agrees to take him to fight Gotenks. Piccolo and Gotenks confront him in the hyperbolic time chamber, but when Piccolo sees they can't win he blows up the door locking everyone in the chamber.
Out of pure anger and hate, Buu yells and creates a rip in the time chamber which leads back to Earth which everyone escapes from. The two battle each other again until Super Buu absorbs them both. When Gohan comes back from training with Old Kai, he is able to match Super Buu's power. When Goku comes back he offers to fuse with Gohan, but before they can Buu abosorbs Gohan, increasing his power even more.
Goku then finds that Vegeta has returned and convinces him to fuse with him, making Vegito. Vegito fights Super Buu and ends up being turned into chocolate, Vegito was able to put up a fight in this form, but was eveentually eaten. The fusion of Vegito is broken. Goku and Vegeta travel to Buu's head and releases all the pods containing the Z-Fighters and the good Majin Buu.
True Form - Kid Buu
As Goku and Vegeta attempt to break out Majin Buu from inside Super Buu, Buu freaks out. Exploding in anger Buu returns to his original from, Kid Buu. He originally became Super Buu by absorbing the North, West and South Kais. He became the Fat Buu when he absorbed the South Kai. Fat Buu was child like and was able to be good because the South Kai was a big jolly soul, sort of like Santa Claus. Without him, Buu reverted to his original form - pure evil.
When Goku and Vegeta broke out they saw Buu's true from. Buu then started to form an attack to destroy the Earth. Unable to stop it go was going to use his instant trasmission to get everyone he could off the planet. Unable to grab everyone, he was only able to take Vegeta, Hercule, and Dende with him. Buu's attack destroyed the Planet, and he then started going from planet to planet searching for Goku. He finally arrived in Other World where he was about to destroy it until Goku and Vegeta powered up so that he would sense them. Buu flies to Supreme Kai's planet where he battles Goku.
During the middle of this fight Kid Buu spit out something that looked like a piece of bubble gum, it turns out it was Fat Buu. Vegeta and Fat Buu take turns in trying to defeat the mighty Kid Buu. Unable to defeat Buu, Vegeta takes over the battle while Goku attempts to form a Spirit Bomb. While they were doing that Dende and Supreme Kai, travel to Namek where they use the Dragonballs to wish everyone who was killed by Buu back to life. Goku then uses the energy of both Earth and Namek to from the Ultimate Spirit Bomb. Powering up to SSJ, Goku throws the Spirit Bomb, while kills Kid Buu.
Buu is brought back because King Yemma owes Goku a favor. So he is reborn as a young child named Uub from a small poor vilage. Uub enters the World Martial Arts Tornament. In this tornament Goku asks the original Majin Buu (who is now calling himself Mr. Buu) to make sure that he fights Uub. when the fight begins Uub is frightened. It is not untill Goku starts making fun of his family that Uub starts to unleash his real power. Goku flies in to the air and relizes that Uub doesn't know how to fly yet. Goku offers to train Uub at Kami's Look Out. They train there for ten years.
When the training ended is when G.T. begins. after goku retrieves the Black Star Dragonballs, Baby comes and steals them. Uub and Mr. Buu help the fight against Baby. at one point when they feared that there was no hope Mr. Buu told Uub that they were once a single being and that inorder to regain their full power they must become one once again. They do this creating Majuub. Majuub has the same strength and potential as Kid Buu, but in Uub's body. Uub then gains the ability to transform things in to candy, particualy chocolate. He accidently turns himself into chocolate however.
Powers & Abilities
Body Manipulation and Regeneration