Frieza

Frieza was one of the most important villains in the DBZ series. He was the one who during combat changed under three different forms to become stronger and who was looking for the Dragonballs so that he could wish for immortality. Frieza hates all Sayajins and in particulary Vegeta who he kills with Dende. At first during the combat between Goku and Frieza Goku believes that he has killed Frieza with his techinque called the Genki-Dama but Frieza came back more powerful than before and he killed Krillin to anger Goku. After killing Killin Goku transformed for the fist time into the legendary super Sayajin. Goku killed Frieza but Frieza had the time to destroy the planet Namek. However one year later Frieza came back to earth under a robotic form and was later on killed by Trunks.