Lennox Lewis had an Iron Chin

Only Valuev has a pure granite chin.
[ame]http://www.youtube.com/watch?v=AEiz9E6dp5U[/ame]

Haye his best shot right on the jaw and the only thing that happened was a chicken dance and a broken hand.
That's just insane.

He could also bounce a lot of punches just straight off his head.

You have Chuvalo (Actually pretty untested as he was a very good defensive fighter, he could take punches better than most people, but his defence was his biggest gift) and then you have SNV.