Henry Clark was never floored, and this is a heavyweight who went seven rounds with Liston, 12 with Shavers, ten with Mac Foster, just over eight with Merritt, ten with Mercado, nine with Norton, ten with Leotis, 12 with Machen, ten with Folley, and he squared off with a few other quality opponents. (He did defeat Machen, Merritt, Foster, Martin, Tiger Williams and Ramos, among others.) In some ways, Clark's remaining upright through to the conclusion of his 50 fight career against Mercado is as impressive as Chuvalo's 93 fight streak, based on Shavers, Mercado, Foster and Martin alone. (Chuvalo did fight some impressive punchers, but did they quite measure up to that lineup?)
Fair or not, I never could have considered David for that distinction after viewing this: [ame]http://www.youtube.com/watch?v=Ja71FoZQrfY[/ame]
Camacho also floored by Reyes Cruz in 1988. He may have had a good chin, but after Rosario hurt him he basically fought the rest of his career as if he was scared to take a punch.
Marvin Hagler was officially down once in his career (against Roldan), but that was a BS call. Of present day fighters with a long career at top level I can mention that Mikkel Kessler never has been down.
Nobody counts Roldan, any more than Wepner is popularly credited for dropping Ali. Bonavena gets more credit for sending Chuvalo to the deck than either of those two get for Hagler and Ali. I can't find any record of single lunged, multiple Lonsdale Belt winning featherweight legend Nel Tarleton ever getting floored in 147 fights. (That's to say nothing of the fact Nella was never stopped by cuts or anything else. Today's pansies gas out with two good lungs inside of a 12 round maximum limit. Tarleton went the championship distance a few dozen times.) Before anybody brings up Billy Graham again, Gavilan was credited with knocking him down in round two and again in round 14 of their fourth and final bout in Havana. There's some question about the validity of the first knockdown, having occurred as the result of a slip and concurrent hook to the body. No ambiguity about the second one though, as a hard right drove Billy to a knee after Graham had been staggered by a previous right. Gavilan gets credit for an all time chin, having been floored once by Ike Williams and then Basilio, before retiring with a total of 143 bouts. But in Panama Al Brown's 168 bouts, I can only find evidence of hard punching Italian Dominico Bernasconi dropping him once in each of their first two bouts. (For his part, Bernasconi was never stopped in 69 matches, and I've not been able to locate evidence that he ever sustained a knockdown.) Alphonso Brown is criminally overlooked when discussing all time punch resistance. (Forgetting that chin for a moment, a relatively remote target at 118, one would think his long body consequently vulnerable. Nope, and don't think opponents didn't try to exploit it in that era.) Getting past 150 bouts without ever sustaining a stoppage defeat is like summiting Everest multiple times without supplementary oxygen.