We first hear about him when Bulma, Krillin and Gohan encounter a strange planet whilst heading for Namek. The people there fear them because they think that they are Freeza's henchman. They describe Freeza as a terrifying being, eager to kill.
Freeza is an evil being who conquers valuable planets to sell them. He uses different warriors from out the entire universe. He also uses Sayians like Vegeta and Nappa to vaporize a planets inhabitents. He has a brother named Kooler and is (almost destroyed) by Goku; finnaly by Trunks.