Wladimir Klitschko is a Ukrainian former professional boxer who competed from 1996 to 2017. He held the world heavyweight championship twice, including the unified WBA (Super), IBF, WBO, IBO, and Ring magazine titles. A strategic and intelligent boxer, Klitschko is considered to be one of the greatest heavyweight champions of all time. He was known for his exceptional knockout power, using a strong jab, straight right hand and left hook, quick hand speed, great physical strength which he employed when clinching opponents, and his athletic footwork and mobility, unusual for boxers of his size.

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.