Heavyweight unification series Heavyweight unification series The heavyweight unification series, also known as the Heavyweight World Series, was a sequence of professional boxing matches held in 1986 and 1987 to crown an undisputed champion of the heavyweight class. The series was produced by HBO Sports and promoted by Don King. It ended with Mike Tyson as undisputed champion, holding the championship belts of the International Boxing Federation, World Boxing Association, and World Boxing Council. Prior to the series, the last undisputed heavyweight champion had been Leon Spinks, who won the championship in his 1978 victory over Muhammad Ali. Spinks had been stripped of
Heavyweight Heavyweight Heavyweight is a weight class in combat sports. Boxers who weigh 200 pounds and over (14 st 3 lb, 90 kg) are considered heavyweights by the major professional boxing organizations: the International Boxing Federation, the World Boxing Association, the World Boxing Council, and the World Boxing Organization. For most boxing organizations, the maximum weight for a cruiserweight is 200 pounds. Thus, a fighter whose weight is over 200 lb (14 st 3 lb, 90 kg) may not fight as anything but a heavyweight. Joe Louis holds the record for most consecutive title defenses at this division, with 25 defenses