Throughout the entirety of "Dragon Ball Z", Goku only kills two characters: a miniboss named Yakon and Kid Buu.

The statement is true because throughout the entirety of Dragon Ball Z, Goku only kills two characters, Yakon and Kid Buu. Yakon was a miniboss encountered in Babidi's spaceship during the Majin Buu Saga. Though Goku engages in numerous battles and defeats many enemies, he typically opts to spare their lives or lets others finish them off. Kid Buu, on the other hand, is the final and most dangerous form of Majin Buu. After an intense battle, Goku destroys Kid Buu using a Spirit Bomb attack, effectively killing him. These are the only instances where Goku directly takes the lives of his opponents in Dragon Ball Z.