Hard not to put The Rock, The Greatest, and SRL at the tops for me. Probably some more, those guys are at the top of my head. Whenever we thought they were gonna lose in any capacity, when things in a fight were bleakest, or when they were underdogs, they usually found a way to come up roses. Rocky Marciano's nose. Enough said. But if you want to say more, look at the skill deficit he was at for all of his big wins. Short arms, little outfighting ability, and a sub-world class defense. And yet, through will, conditioning, and a never-say-die attitude, he couldn't be stopped. The pain he was willing to endure to win might be, historically, unparalleled. Ali was the most dangerous underdog in heavyweight history, and possibly boxing history. He won his title as an underdog, and walked through blindness. He won it back as an underdog, allowing himself to take a pounding to wear his foe out. And he frequently battled through a crazy amount of adversity after that (Thrilla, Norton III, Shavers, etc) to win when it seriously looked like he shouldn't. I've never seen a fighter "come up with it" like Leonard in the Hearns fight. He was dead to rights against one of the most studly welterweights ever, way behind on points, unable to see out of his lead eye, and manages to dig down and get a stoppage against a previously invincible juggernaught. Thats nuts.
Well said Magna, I think you covered the best in this category. Not necessarily a clutch-ness, but a smartness that allowed for Moore to come out on a lot of tough fights might make him a decent inclusion. I think Gatti might be a pretty good, obvious mention. Hell, Mickey Ward's not an awful mention either, although I guess we're straying too far from the core of the topic which is clutchness, not best heart. Who can pull it off, and sometimes that takes heart, will, and a degree of timing and intelligence.
Monzon definitly has to be mentioned. Whitaker too, see Hurtado. Ottke actually as a seious mention works too, see Mundine.
Duran deserves a mention. No, really. When Roberto was in a fight, he almost always won. This was even more evident when he was older against Barkley, Camacho and Pazienza. Simply said, name a really close battle he lost on points? There's Hagler, but I think he did as well as he could have against a candidate for best ever at that particular weight. Edit: I also think this is the defining attribute to seperate the toughness Muhammad Ali had from, say, Tyson. Tyson could take a lot, but he couldn't get the W in a war ' cept for Ruddock.
Marciano. No one else does what he did in Walcott fight, he was blinded by some chemical in middle rounds, still hung in, came back. In 2nd Charles fight, that do-or-die KO was amazing, and in first bout with Charles, he put on some display to sweep most or all of late rounds. Very clutch.
Sal Sanchez has not been mentioned yet. When things got tough late or dicey, that was a guy that rose to the ocassion.
Julian Jackson seemed to have to come back from adversity in every single win he had, so him. It's as if he wasn't interested unless things weren't tough.
Rocky Marciano...the title fight with Joe Walcott in 1952...and the second fight with Ezzard Charles in 1954...'nuff said...