1 Muhammad Ali:

Originally Cassius Clay he was undoubtedly the Greatest, winning the title in 1964 and again in 1978.

2 John L Sullivan: The American was the first champion in 1885 in a bare-knuckle fight.

3 Jack Johnson: The first African American to win the title in 1908.

4 Jack Dempsey: One of the greatest ever, the Manassa Mauler was a hero figure to many Americans.

5 Joe Louis: The Brown Bomber defended the championship a record 25 times.

6 Rocky Marciano: The only fighter to hold the title and go undefeated throughout his career.

7 Floyd Paterson:

The youngest man to hold the title at 21, and the first to regain it.

8 Sonny Liston: Hard puncher with some underworld connections who famously lost to Clay in 1964.

9 Joe Frazier: Smokin' Joe defeated Ali in the Fight of the Century, in New York, in 1970.

10 George Foreman: Lost to Ali in the Rumble in the Jungle before inventing the George Foreman Grill.