The Comedian

Played by Jeffrey Dean Morgan in Zack Snyder's Watchmen, the Comedian is a nihilistic character who doesn’t believe that man can be good. And this justifies his violent ways "“ he isn’t a vigilante because he wants justice; he’s a vigilante because it pays, and because he likes hurting people.

In the most shocking scene in the movie (appearing in the comics as well), he kills the woman who bore his child without even flinching. He even mocks her before pulling the trigger. What reason could there be for such a gesture? He does it just to test Manhattan's humanity.

In the comics, the Comedian also kills an entire drug ring with a baseball bat (Jeffrey Dean Morgan has gone on to play The Walking Dead’s Negan, who’s famous for his baseball bat, which he’s named Lucille). He also kills seven prisoners of war on a bet.

So, yes, the Comedian is a pretty violent hero.