Evander Holyfield is an American former professional boxer who competed between 1984 and 2011. He reigned as the undisputed champion at cruiserweight in the late 1980s and at heavyweight in the early 1990s, and is the only boxer in history to win the undisputed championship in two weight classes in the three belt era. Nicknamed "the Real Deal", Holyfield is the only four-time world heavyweight champion, having held the unified WBA, WBC, and IBF titles from 1990 to 1992, the WBA and IBF titles again from 1993 to 1994, the WBA title a third time from 1996 to 1999; the IBF title a third time from 1997 to 1999 and the WBA title for a fourth time from 2000 to 2001.

In boxing, the undisputed champion of a weight class is the boxer who simultaneously holds world titles from all recognized major organisations by each other and the International Boxing Hall of Fame. There are currently four major sanctioning bodies: WBA, WBC, IBF and WBO. There were many undisputed champions before the number of major sanctioning bodies recognizing each other increased to four in 2007, but there have only been 19 boxers to hold all four titles simultaneously.