In the 1980s Mike Tyson emerged as a serious contender. Nicknamed "Iron Mike", Tyson won the heavyweight unification series to become world heavyweight champion at the age of 20 and the first undisputed champion in a decade. Tyson soon became the most widely known boxer since Ali due to an aura of unrestrained ferocity, such as that exuded by Jack Dempsey or Sonny Liston. His career culminated in Evander Holyfield vs. Mike Tyson II where he famously bit off a piece of Holyfield's ear.