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Michael Spinks

1985-88

Spinks joined older brother Leon to become the first pair of brothers to win the heavyweight championship (a feat later equaled by Wladimir and Vitali Klitschko).

A middleweight gold medalist at the 1976 Montreal Olympics, Spinks ran off 27 consecutive victories as a professional. Then, in his first bout at heavyweight, Spinks upset unbeaten Larry Holmes in 1985 to become the first reigning light heavyweight champion to win the heavyweight crown. Spinks, who seven months later would win a rematch by split decision (which was as disputed as the first Holmes fight), retired in 1988 after his only loss, a first-round knockout to Mike Tyson in 91 seconds.