Frieza

As the strongest being in the universe during his time, Frieza is solely responsible for the destruction of Planet Vegeta along with almost all of the Saiyan race. He and his armies purge planets of life, and sell them to the highest bidders, or he may just blow it up. Frieza sees himself as the most powerful being in the universe, with no equal. Frieza's greatest fear was the Saiyan race, not only because they were the strongest species he had ever encountered by far in all the universe, but he also feared them because of an ancient legend among their people. Because the Saiyan race was already so powerful and great in number, Frieza could not believe how powerful a Super Saiyan might be, and so this is why he decides to destroy their planet. It was said that every few thousand years or so, a super-powerful Saiyan was born to their people, the legendary Super Saiyan. After he hears about the Dragon Balls, he travels to Planet Namek in order to wish for immortality. When he is on Namek he encounters Vegeta, Goku, Gohan, Piccolo, and Krillin. He has several forms in order to conserve energy, and rarely uses his true form. We see all of Frieza's transformations and he is forced to go to his highest level in order to beat the Saiyans. After a long battle, he is defeated, but not killed, by Goku. His father (King Cold) finds him, nearly dead, floating near the remains of Planet Namek and takes him back to his planet in order to save him. After being restored with robotic parts, Frieza and his father travel to earth to exact revenge on the Saiyan that beat him and it is there that Frieza finally meets his end by the blade of Trunk's sword. After Frieza is killed King Cold tries to recruit Trunks to work alongside King Cold as partners. Trunks obviously refuses and kills King Cold easily.