10. Captain America
During Marvel's first "Civil War," the Punisher had a little run-in with Captain America after he gunned down two criminals who attempted to join forces with Cap's anti-registration group. Cap immediately began pummeling the Punisher, but he didn't fight back. For Frank Castle, Captain America is his hero, so he wouldn't raise his fists to the man.
That's what went down on Earth-616, but over on Earth-11080, Cap and the Punisher's confrontation didn't end as well. In that alternate reality, a virus swept across the planet, infecting everyone. Instead of making them sick or killing them, the virus turned everyone into cannibals.
The virus infected superpowered folks as well, so Captain America organized a squad of himself, Punisher, Deadpool, and Wolverine in an attempt to stop the Hulk and his faction. When they fail to find the Hulk, the team split up, leaving Cap and Castle alone to fight the Hulk's mob.
Before long, Cap started showing signs of infection, but he still maintained some control over his mental faculties. Realizing he was infected, Cap knelt down on the floor and asked Castle to kill him before he fully turned. Before he pulled the trigger, Castle informed Cap that he always was his hero.