Greatest of all time would have to go to Walker Smith AKA Sugar Ray Robinson. The epitome of the sweet science and completely ruled the Welterweight and middleweight divisions in his prime. Even bounced back to regain world titles 5 times after losses etc. Almost won a light heavyweight world title as well before succumbing to the heat. There would be no Ali without pioneers like Robinson. Complete package.

The hero and the coward both feel the same thing, but the hero uses his fear, projects it onto his opponent, while the coward runs. It's the same thing, fear, but it's what you do with it that matters. Cus D'Amato