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 boxing championship records and statistics minimum weight for a heavyweight was set at 175 pounds (12 st 7 lb, 79 kg), which today is the light heavyweight division maximum. Since 1980, for most boxing organizations, the maximum weight for a cruiserweight has been 200 pounds. 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. Since the 1960s, the heavyweight title has become fractured amongst various sanctioning organizations, and so what was once known as the