this is also a comic game, so the complexity is skipped by the genre 😛
Dexter is a Villain, he doesn't kill for the greater good (Vigilante) he kills other villains to hide his own crimes, I will go out on a bit of a limb and claim the Punisher is NOT a vigilante, I would characterise him as a rogue at best, bordering on villain, he kills not (again) for the greater good, but revenge 😄