Oleksandr Oleksandrovych Usyk (Ukrainian: Олекса́ндр Олекса́ндрович У́сик) is a Ukrainian professional boxer. He has reigned as the undisputed cruiserweight champion since July 2018, being the first boxer in history to hold all four major world championships at cruiserweight: the WBO title since 2016, the WBC title since January 2018, and the WBA (Super) and IBF titles since July 2018. Three of these titles were won during the inaugural World Boxing Super Series, in which Usyk won the Muhammad Ali Trophy. As of July 2018, he also holds the Ring magazine and lineal titles.
Usyk is the most recent male boxer to simultaneously hold the WBA, WBC, IBF and WBO titles since Terence Crawford in 2017, and is one of only five boxers in history to do so after Crawford, Jermain Taylor, Bernard Hopkins, and Cecilia Brækhus. Usyk won the undisputed championship in his 15th professional fight, which is an all-time boxing record, and is the first undisputed champion from Ukraine. As an amateur, he won gold medals at the 2011 World Championships and 2012 Olympics, both in the heavyweight division.