Nappa is a sayian warrior who worked with Vegeta his whole life. In his lifetime he conquered planets along side of Vegeta and Raditz for the evil Frieza.Nappa didnt accomplish much in his life and if it wasnt for Goku knocking hium out then vegeta blasting him to the next dimension during the frieza saga even the weakest Z - Fighter Chaotsu could have killed him without a problem.
