Looking back only a few years, a few fighters come to mind. Sergio Martinez KO Paul Williams. This knockout gave him both vindication, and turned him into somewhat of a superstar. As good as Martinez was, his resume is thin. Without the sickening KO of Williams, he would've passed through relatively unnoticed by casual fans. Nonito Donaire KO Montiel. Another nasty KO, another star making performance. Nonito fell in love with his power after this fight, if he hadn't already. This fight transformed him from pretty good KO artist to the next Pacquiao. In the end, both guys had VERY inflated p4p rankings. Donaire suffered a humbling boxing lesson that made him irrelevant, and Martinez rapidly withered leaving us to wonder how good he really ways.
Allan Green. Once he scored the devastating KO over Jaidron Codrington...!!! Green-a relative up-and-comer was quickly thrust into bigger fights in the future. Fighting the likes of "Pantera" Miranda, Tarvis Simms, Ward, Glen Johnson, Kessler...!!!