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
Light heavyweight heavyweight division and became undisputed champion of the latter two. Dariusz Michalczewski holds the record for most consecutive title defenses at this division, with 23 defenses of the WBO title. Current champions Below is a list of longest reigning light heavyweight champions in boxing measured by the individual's longest reign. Career total time as champion (for multiple time champions) does not apply. In MMA, the light heavyweight division is from 186 lbs (84 kg) to 205 lb (93 kg). Light heavyweight Light heavyweight, or junior cruiserweight, is a weight class in combat sports. In amateur boxing, light heavyweight is a