Would you call Wolverine, Deadpool, etc. villains or anti-heros?
It's not just about "murdering people". Yes, that is obviously BAD, but we also look at their motives. How many movies have we seen where, frex, cops = good guys kill the bad guys? Why are they killing the bad guy? Is it to prevent future deaths by the evil person's hand? Or in self-defense?
There's a scale here. On the "whitest" side you have Superman. Batman would be entering a light shade of grey b/c he's still a vigilante and he still uses torture tactics to get information out of perps (as well breaking and entering, etc.). Catwoman, whose MO isn't to kill, is further down the grey scale b/c she steals (but at times has done it for a purpose involving betterment of animals). Wolverine, Punisher, Jason, Deadpool would be in that anti-hero category b/c they kill. Then there's the darker scale of villains, etc., etc.