Sam Langford
Sam Langford had absolutely devastating power, but is often overlooked due to the fact that he was denied many opportunities as a result of the pervasive racism in the sport at the time.
Even Jack Johnson, a fellow black fighter and heavyweight champion, refused to fight him once he became champion. Langford did however compete for, and win, the World Colored Heavyweight Championship on five occasions.
Langford holds victories over Stanley Ketchel at middleweight, and many feel he deserved one when he fought Jack Johnson before he won the world championship. It was a close fight, and Johnson got the nod, but many felt this was the wrong decision.