Buu is probably the strongest villain in Dragonball Z history. Many eons ago, Buu was under the control of Bibidi and Buu did whatever Bibidi pleased. Buu rampaged through the universe, killing and destroying everything in his path. The Kaio's were able to seal Majin Buu up inside a sort of speherical orb, which he remained in for many thousands of years. Then, Babidi, son of Bibidi, comes to planet Earth, to continue his fathers plans for universal power. Babidi gathers up enough power through the Z Fighters to release Buu. To put it bluntly, Buu was untouchable, no one had a chance of beating him. He slowly began to absorb the Z Fighters, each time getting stronger, and stronger. Buu has a number of stages, each of which he reaches when he absorbs some people. In total Buu has four stages, he starts off as a somewhat kind person, Fat Buu, then evolves to an eviler form, Super Buu. After absorbing Gohan, Piccolo and Gotenks, he reaches a Super Super Buu, and his final stage is Kid Buu, where he reverts back to his original form. Kid Buu is destroyed by SSJ3 Goku's Spirit Bomb.