Mutants are various alien races who were affected by a serum spread across the galaxy by Dr. Korchin in an effort to destroy the Saiyans and gain an ally for the Tuffles. They started a war with the Saiyans and were defeated but the mutants formed an alliance and joined his army while others joined Cooler, King Cold, and Frieza. This army was the beginning of the Planet Trade Orginization. Some of the mutants that joined him after the battle were Cui, Dodoria, and Zarbon as well as the newly formed Ginyu Force. Several mutants were killed during Sprtatuk's rescue of Fridga's prisoners. Several other mutants were killed during Fridga's attack on Planet Bardock. Vegeta killed several mutants on Namek notably Cui, Dordoria, Zarbon and 4 out of 5 members of the Ginyu Force as well as all or most of the members of Frieza's army. Future Trunks later killed several mutants with his sword when King Cold and Frieza arrived on Earth. The last known surviving mutants were either killed in the attack on New Planet Bardock or killed by Turnarrot or the Z fighters during Fridga's attack on Earth. Salza, Neiz, Doore were also mutants but as the canoncity of Cooler's Revenge is debatable it is unclear whether Piccolo killed them in the main timeline or not. Anyone who did or does not fight such as some of Frieza's doctors are not mutants but rather survivors of attacks on their planet by Saiyans. The unnamed bird race that Vegeta slaughtered may have been mutants as well but it's unclear if they have powers or not.