Frieza is a villian with an ego bigger than Vegeta and who's only purpose is to destroy. He is left for dead after battling Goku on Namek. Frieza kills Krillin, sending Goku into a rage and causing his Super-Saya-Jin transformation for the very first time. Frieza later appears on Earth, after being restored by his father, King Cold, where he is sliced in two by the future version of Trunks.
DBZ Bad Guys - Frieza
From Katherine Luther, former About.com Guide
Frieza - Dragon Ball Z - Image Courtesy of FUNimation
FUNimation