This question pops up pretty frequently on these boards. The answer is Victor Oganov. In his amateur career, every single victory (64 of them) was inside the distance. That's pretty incredible. In his pro career, his first 26 fights were wins inside the distance. However, he is a totally atrocious fighter. As soon as he got in the ring with people who weren't bums and who didn't just stand still for him to land flush power shots on - that's when he started to get his ass kicked. Victor Oganov has the hardest pound for pound punch. But it is useless to him, cause he doesn't have the skill to hit anyone who is worth hitting.