Wladimir Klitschko ( Ukrainian: Володи́мир Володи́мирович Кличко́; born 25 March 1976) is a Ukrainian heavyweight professional boxer . Klitschko is the current Transnational Boxing Rankings Board, lineal, WBA (Super), IBF, WBO, IBO and The Ring world champion (see List of heavyweight boxing champions .) Klitschko is the longest reigning IBF, WBO & IBO heavyweight champion in history with the most title defenses for those organizations. Overall, he is the second longest reigning Heavyweight Champion of all time with the second most successful grand total title defenses with 21 (including his "super" title recognition). On 13 October 2013, Boxrec rated Klitschko as the number two pound-for-pound fighter in the world. On 15 April 2014, he reached a career peak of number three on the pound-for-pound list of Ring Magazine . Klitschko is tied with Muhammad Ali for second on the all-time list for most heavyweight title fights with 25, behind only Joe Louis with 27. He is the younger brother of former WBC, WBO & Ring magazine heavyweight champion Vitali Klitschko .