Punisher

"They laugh at the law. The rich ones who buy it and twist it to their whims. The other ones, who have nothing to lose, who don't care about themselves, or other people. All the ones who think they're above the law, or outside it, or beyond it. They know all the law is good for is to keep good people in line. And they all laugh. They laugh at the law. But they don't laugh at me."

- The Punisher's speech during Return To Big Nothing.

The Punisher (real name: Frank Castle) is perhaps one of the best examples of an anti-hero - created and owned by Marvel Comics this vigilante is both a protagonist (with his own series and film franchise) and antagonist. He even has also allied himself with the Thunderbolts.

Frank Castle was once an former Marine with a happy life and family, until one fateful and tragic day when he and his family accidentally stumbled upon a gang lynching in a park. His wife and children were gunned down and he was left for dead. Horribly scarred for life, Castle swore to "punish" all criminals in any way possible, and became a violent vigilante hellbent on wiping crime off the face of the earth.

The Punisher is a borderline sociopath who is obsessed with destroying criminals - he does not just solve crime, he brutally punishes those who commit such acts. What makes the Punisher stand out from most anti-heroes is his tendency to utilize murder, kidnapping, torture, coercion, extortion, and other illegal methods to get the job done and he is rightfully feared and respected by those who know of him.

The Punisher has always been blurred between the distinction of "good" and "evil" but is as worthy of note as any other anti-hero in fiction (especially given his brutal nature).

Despite his faults, the Punisher does not wish for anyone else to follow in his own footsteps and he will not kill innocent people unless he knows they are secretly evil.

Punisher Media
The Punisher is one of Marvel's most popular anti-heroes and has appeared in a great many media outwith his origins as a comic book character. Despite the character being one of Marvel's most "mature" titles due to its graphic violence and controversial themes, the Punisher himself has appeared in media that is geared towards younger audiences, though his personality is often softened somewhat and/or his violence toned down.

Comics
The Punisher has become a large part of the Marvel universe and as such has appeared in many comics, spanning several years - as with many comic book characters The Punisher has went through many drastic changes in the course of his "career" (due to different takes on the character), he also has several alternate origins and "reboots" which further change his character, meaning that different stories can portray him in very different lights.

Movies
The Punisher starred in his own movie series, which depicted him as the protagonist - however much like in the comics he is not a classical "hero" and commits acts that could be seen as immoral if not for the fact the people he fought were much worse than himself (a case of "evil versus evil").