The Punisher has an interesting history in Marvel comics, beginning as a Spider-Man villain before being gradually turned into an anti-hero. His origin story is well known by now: Frank Castle, a former soldier, finds his family deceased after a mob hit that was meant for him. Using this grief to fuel his vengeance, he set out to terminate pretty much every violent criminal he could find. This, obviously, is a distortion of justice, and his rehabilitation into something resembling a hero embraced even by some cops bothers his creator, Gerry Conway.