10.Mike Tyson
The youngest ever to win the title. 44 of his 50 wins were by knockouts. KO'd Michael Spinks in 91 seconds.
9. Wladimir Klitschko
1996 Olympic Gold Medalist. WBA, IBF, WBO and IBO Champion. Most title defenses in history.
8. Lennox Lewis
7. Jack Dempsey
Champion from 1919 to 1926. 51 of his 66 wins were by knockouts. Knownis aggression and furosity.
6. Joe Frazier
1964 Olympic Gold Medalist. Defeated Muhamad Ali. 27f his 32 wins by knockouts.
5. Larry Holmes
WBC and IBF Heavyweight Champion. He made 20 succesful title defenses. Almost matched Marciano's 49-0 record.
4. Rocky Marciano
He is the only undefeated champion. 43 of his 49 wins were by knockouts. He knocked out Joe Louis.
3. George Foreman
1968 Olympic Gold Medalist. He was a two-time Heavyweight Champion. He defeated Joe Frazier(twice).
2. Joe Louis
World Champion from 1937 to 1949. He was victorious in 25 title defenses. His reign lasted 140 consecutive months.
1. Muhammad Ali
1960 Olympic Gold Medalist. 3 time World Heavyweight Champion. He defeated Joe Frazier and Sonny Liston twice. He knocked out George Foreman.