I was gonna say frankie vs gray. that is always up there.
however, i think i have a new champ in my mind for this particular category.
Im going with the count when he agreed to fight and then KO rockhold in their second fight.
hear me out you haters!!
mike was trolled by a loyal legion of haters for years, and got beat by rockhold, and people continued to troll, bully, pick on and disrespect the count.
then, he was presented the chance to fight rockhold a second time, having been battered, beaten, and brutally choked out in their first meeting. and he took it!! what heart, what courage, what intestinal fortitude, and this was a short notice fight for him--luke had a fight announced and was readying himself for a fight--when this fight was announced, luke stepped of the gym he was already in to confirm, whereas the Count had to get off of his couch to confirm.
Despite the vitriol and venom that was surrounded and followed the now champ, he refused to give in, he prepared himself, he shut out the haters, the naysayers, and teh detractors, and he fought luke rockhold in unfriendly and unfamiliar territory, after a short fight camp, and he knocked luke out with a blistering barrage of concussive blows.
Mike's claim to the title dwarfs any and all of the rocky movies.
tehe champ's performance and the courage to take the fight, let alone show up and dare to be awesome, all embody a fighter's heart.