This one's actually going to call for some research. Now you've successfully distracted me for a week!
On paper:
Hulk
Superman
Green Lantern
Mr Marvellous or summat
One on fanboy site they said Batman wouldn't even beat Wolverine in a fist fight so he's nowhere on this one sadly.
Bane broke Batman's back. I think on a physical and metaphorical level he kind of wins. Noone can crush the bat's spine without bragging rights for life, and a sworn enemy in Govi*.
Ok ok, flimsy, but lemme think...
Found an interesting conversation here.
Superhero Fanboy gaynessAnd of course there's the alien Doomsday who destroys metropolis, is completely unstoppable and beats the living crap out of Superman in the animated feature...'Doomsday'. Pretty grim watching if you've ever seen it - Superman gets beaten up so bad, blood spatters a-la Tarantino (for as far superhero films go) and he actually dies from getting smacked with the best part of a city's infrastructure. He'd get my vote. But does this question go for Superbaddies too?
For this question you'd have to go back to the sixties comics I think - in those they were all about sizing up. These days it kind of more mundane with pressing questions like what Peter Parker's daughter wants to accessorise with her iPod.
I saw Marvel Chronicles yesterday - 30 squid. I will own it one day. If anyone sees it in the shops look up 'Marvel's strongest bastard' in the index. report back.
lalala