A supremely gifted British heavy from the 90's. Had all the gifts,speed,timing,power and grace. He did,however,make Bruce Seldon look rugged and tough in comparison.
Probably Alphonse "Canvasback" McGoon, a New Jersey heavy from the turn of the century who was ko'd once during the referee's instructions.
Lennox Lewis had worst of heavy champs. Roy Jones was pretty weak in chin department. Old man Mayweather, who was ko'd by Rocky Lockridge had awful chin. Breland belongs on this list too. For journymen and trial horses I'll mention Bobby Crabtree, who had strange chin. To explain, he would usually give a few good rounds, even take a good punch early, but if a fight went on past 4 rounds, he would often go down from slightest shot.
Mark Bliss. You don't know him, and that's one reason why. http://www.boxrec.com/boxer_display.php?boxer_id=53778
Fraudley's chin is worse than Grant's. At least to expose his glass jaw, it took rated fighters. A-Farce may even have a shakier chin than Hide!!!:yep
Well, if we're taking tomato cans into account, then this guy HAS to have the worst chin EVER in boxing history. His name must have been DESTINY! Look at how many times he was knocked out, and WHEN he was knocked out: www.boxrec.com/boxer_display.php?boxer_id=5316