The 10 Last Undisputed World Heavywieght Boxing Champions

1. Mike Tyson
Reign Began : August 1 1987
Reign Ended : May 6 1989
(Tyson held the WBC, WBA and IBF titles from August 1 1987 to February 11 1990 and was generally acknowledge as the universal champion despite the fact that a new body, the WBO, came into being in 1988 and had it's first heavyweight champion (Francesco Damiani of Italy) on May 6 1989.)

2. Leon Spinks
Reign Began : February 15 1978
Reign Ended : March 18 1978
(Spinks was stripper of his title by the WBC for refusing to fight their No. 1 contender Ken Norton.)

3. Muhammad Ali
Reign Began : October 30 1974
Reign Ended : February 15 1978

4. George Foreman
Reign Began : January 22 1973
Reign Ended : October 30 1974

5. Joe Frazier
Reign Began : February 16 1970
Reign Ended : January 22 1973

6. Muhammad Ali
Reign Began : August 1 1987
Reign Ended : May 6 1989
(Ali was stripped of his title by the WBA and then WBC for failing to be drafted in to the US Army.)

7. Casius Clay(later became Muhammad Ali)
Reign Began : February 25 1964
Reign Ended : June 19 1964
(The WBA withdrew recognition of Ali after refusing a re match with Sonny Liston.)

8. Sonny Liston
Reign Began : September 25 1962
Reign Ended : February 25 1964

9. Floyd Patterson
Reign Began : June 20 1960
Reign Ended : September 25 1962

10. Ingemar Johansson
Reign Began : June 29 1959
Reign Ended : June 20 1960