I have to go with Wolverine. First off, you can't kill the man. He was ripped in half by the hulk, had the adimantium pulled out of his body by Magneto twice, and survived being in ground zero of a nuke (he regenerated from some still living brain matter or something like that.) He smokes like a chimney, and was born in the 1800's. His skeliton is also encased in solid adimantium, which makes his skeleton unbreakable. Second off, he's an amazing fighter. He takes a lot of street fighting tactics and mixes them with martial arts, and his heightened senses aid him in combat, he's able to see attacks coming and can defend himself much better than many people. He's also a great assassin. He can sneak around and use his heightened senses to track people from much further away than anyone else.