Leon Spinks was an American professional boxer who competed from 1977 to 1995. In only his eighth professional fight, he won the undisputed heavyweight championship in 1978 after defeating Muhammad Ali in a split decision, in what is considered one of the biggest upsets in heavyweight boxing history. Spinks was later stripped of the WBC title for facing Ali in an unapproved rematch seven months later, which he lost by a unanimous decision. World heavyweight champion (WBA and WBC) from February 15, 1978 to March 18, 1978. Wiki link