Trunks

Frieza took an entire saga to beat. Planets died, Goku transformed for the first time, the whole thing ran for months. Then a kid with purple hair lands, says nothing, and cuts him in half. Twenty seconds. Then he kills Frieza's father too, sits down on the grass and waits for Goku to show up so he can hand him some medicine. He came from a future where the androids killed everyone he knew. Gohan raised him and died for it. His father never met him. He travelled back not to save his own world, which was already gone, but to make sure this one never got there. He warned us. Nobody had asked him to.