6. Conan The Barbarian Vs Wolverine
I wanted to include one "What If?" example in this list and my favourite hero versus hero example from the "What If?" line is undoubtedly "What if Wolverine battled Conan the Barbarian?" In this comic, when Wolverine is on the moon fighting alongside the other X-Men, Uatu the Watcher sends him to the world of the Hyborian age. Wolverine encounters Red Sonja, who he first fights and defeats, but then finds himself attracted to her. When Conan shows up, not too pleased about this newcomer messing with his would-be girl, he attacks Wolverine but gets his hand cut off by his claws. Conan, being a hard-ass son-of-a-bitch, immediately sticks his bloody stump in to a burning brazier and cauterises the wound there and then. After a little bit more action, Conan gets zapped away in the same way that Wolverine had been zapped away in the first place, and it is implied that Wolverine has taken Conan's place, becoming King of Aquilonia with Red Sonja as his wife. Then, Conan appears via a portal next to the the X-men who are fighting some bad guys. One-handed, Conan starts shoving his sword into Skrulls and various other enemies, which causes the X-Men to retreat. Okay, there are a lot of ridiculous things going on in that little story, but the basic principle of two heroes from different times battling against each other is one that would be simply fantastic in a live action movie (picture Hugh Jackman's Wolverine against Arnold Schwarzenegger's original Conan and tell me I'm wrong!).