Mike Tyson is a boxer.
Heavyweight is a weight class in boxing and other combat sports . Mike Tyson . He reigned as the undisputed world heavyweight champion and holds the record as the youngest boxer to win a heavyweight title at 20 years , 4 months and 22 days old . In 2002 , Tyson fought for the world heavyweight title again at the age of 35 , losing by knockout to Lennox Lewis . The World Boxing Association ( WBA ) is the oldest and one of four major organizations which sanction world championship boxing bouts , alongside the IBF , WBC and WBO .