Professional boxing knocked him out in brutal fashion. This fight made Hagler famous; he was able to lure Ray Leonard out of retirement in 1987, but lost in a highly-controversial decision. Hagler retired from boxing immediately after that fight. In the latter half of the decade young heavyweight 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
Heavyweight boxing championship records and statistics single "Heavyweight Champion", is now referred to as the "Undisputed Champion" as the one fighter that has defeated all the other titlists. However, there is no officially declared definition of the term, as major boxing organizations refer to all boxers holding at least two world titles in their respective division as "Unified champions". Some title reigns are not recognized as official reigns due to long periods of inactivity, legitimacy of title, false billing and promotion. In March 1967, Muhammad Ali was systematically denied a boxing license in every state and stripped of his passport because of his refusal to be