It's a complex situation. Different storylines and villains have targeted the Avengers, but no one specific character can be said to have killed them all outright.
Kang's demise in comics is a complex matter. It could be a result of a team-up of heroes, or it might be due to an unexpected turn of events involving multiple characters and their actions.
Well, Negan's end in the comics isn't straightforwardly due to one specific killing act. It's more complicated and involves multiple factors and characters' actions.