Good question. I have to respectfully disagree with some of the previous answerers on this. Marciano was a very underrated fighter for one thing and did fight fighters who were fast such as Charles and Walcott. He had a fierce will to win and was obviously very determined and as strong as a 230 lb fighter despite being only around 186 lbs. He also had a very underrated defense and was not the punching bag people seem to make Rocky out to be. And of course he had perhaps the best stamina and endurance of any fighter of that era because of his fabulous conditioning ad could knock an opponent out in any round from 1-15. Now that breing said, Rocky had already fought 49 fights and his wife was wanting him to stop fighting along with having some back problems is why he chose to retire. At the most I don't believe Rocky would have fought past 1958 anyway and would have had perhaps 5 fights at best. People say Patterson could have beaten Rocky? With that chin of his are you kidding? Rocky would have worn Floyd down and knocked him out in 7-8 rounds in my opinion. Floyd didn't even move up to heavyweight until after Marciano's retirement an for good reason. Zora Folley and Eddie Machen weren't as good as Floyd so I see Rocky knocking them out too. Cleveland Williams though bigger than Marciano would not have beaten Marciano in a slugfest and would have also been worn down by Rocky though it would have been a fun fight to see. Sonny Liston is the only guy on here that would have perhaps beaten Marciano because of his thunderous jab but even Liston would have known he was in a fight and that would have probably been Marciano's last fight say about 1958 if it could have happened.

Priming Patterson would have beaten him on points, if not stopped him. Prime time Liston and Williams would have stopped or knocked him out. Marciano was the last of the great smallish heavyweight champions and he would have been outmatched by the then emerging modern heavyweights who have started to master the art and science of combining boxing skills, agility, speed, finesse and unprecedented punching power. Marciano would have even struggled versus Zora Folley.

Except for the then still prime time thjough aging Ezzard Charles and Jersey Joe Walcott, Marciano had never seen the likes of prime time Patterson, Liston, even Williams and Folley.

IMO definitely Liston and Williams would stop him and Folley too or at least out point Marciano. Patterson was very fast, but he of all was the one that might be Ko'd by Rocky.

Sonny Liston. Rocky beats the other 3.

Age

Take your pick. That next generation of heavyweights would have destroyed him.

His next opponent would have likely been Floyd Patterson, could he have stopped Rocky? Or maybe Cleveland Williams, Zora Folley or Sonny Liston? Would he have kept winning up until an old man facing Ali?

Please state why.