Freeza
C'mon, if you don't know who this guy is and you're a Dragon Ball fan, you should probablly crawl out from under the rock you've been hiding beneath. Freeza is of course the biggest scumbag to walk the face of the Universe. He's basically the head of a HUGE "company" that goes around purging planets of life, and then selling them to the highest bidder. Or, if he's so inclined and in the right mood, he may just wipe out a planet for fun. Freeza sees himself as the most powerful being in the Universe, with no equal. However, Freeza's greatest fear was the legendary Super Saiya-jin, and by wiping out all but 3 Saiya-jin, he figured that he would have been safe. Well, yeah, he might have, unfortunately, he missed one. Son Gokou. Freeza has the ability to upgrade his power 3 different times, and each time he upgrades, his body actually changes to become suitable for his power. Once he powers up a third time, he has the ability to charge up to 100% energy which doesn't really change him, it just buffs him out. Freeza is supposedly killed by Son Gokou on Nameck, however, he's found and rebuilt by his father, King Kold. He goes to Earth to seek revenge, and there he's sliced and diced by Trunks and goes to Hell.