The Punisher is (or was) a Marvel comic book "hero". I'm pretty sure he first appeared in a Spiderman comic. The Punisher goes around killing bad guys with automatic weapons and explosives. He'd be really popular in the media during the last few years. Spidey, on the other hand, always tries his best not to kill the bad guys, so he doesn't get along with the Punisher, whom he feels is a criminal. Spiderman has a similar relationship with Michael Morbius and maybe Blade. Anywho, the Punisher's story is that some bad guys (maybe mafia) killed his family. He vows to get revenge and probably kills them all. He then devotes his life to killing as many bad guys as possible.

There's a movie based on this character, 1989's abysmal The Punisher starring Dolph Lundgren. Another in the long list of Marvel movie failures.