Claim: Wladimir Klitschko is a fighter.

Wladimir Wladimirowitsch Klitschko -LRB- Володи́мир Володи́мирович Кличко́ , ; born 25 March 1976 -RRB- is a Ukrainian professional boxer . He is a former world heavyweight champion of three major sanctioning bodies , having held the titles of the WBA , IBF , and WBO -LRB- twice -RRB- ; additionally he has held the IBO , Ring magazine , and lineal heavyweight titles . A strategic and cerebral boxer , Klitschko is considered to be one of the greatest heavyweight champions of all time , as well as among the hardest punching knockout artists in the history of the division ; his strong jab , straight right hand and left hook being his most formidable weapons .   As an amateur , Klitschko represented Ukraine at the 1996 Olympics , winning a gold medal in the super-heavyweight division . After turning professional later that year , he defeated Chris Byrd in 2000 to win the WBO heavyweight title . Klitschko 's first reign as champion ended in an upset knockout loss to Corrie Sanders in 2003 , which was followed by another knockout loss to Lamon Brewster in 2004 . It was during this time that Klitschko hired Emanuel Steward as his trainer , which began an eight-year partnership that lasted until Steward 's death in 2012 . In particular , Steward was credited with Klitschko 's transition from an aggressive puncher to a more defensively-oriented boxer , much as he had done with Lennox Lewis in 1995 to 2003 .   In 2006 , Klitschko regained a portion of the world heavyweight championship after stopping Chris Byrd in a rematch to win the IBF and IBO titles . He won the WBO title for a second time by defeating then-unbeaten champion Sultan Ibragimov in 2008 . Following his defeat of Ruslan Chagaev in 2009 , Klitschko was awarded the Ring and lineal titles , and lastly he won the WBA title from David Haye in 2011 . Until his defeat by Tyson Fury in 2015 , Klitschko was also recognized as champion by the Transnational Boxing Rankings Board , while the WBA recognized him as one of its `` Super champions '' , a distinction given to boxers who hold that title in addition to those by other sanctioning bodies in the same division .   Overall , he became the second-longest reigning heavyweight champion of all time , and has the second-most successful title defenses total of any heavyweight boxer with 23 -LRB- including his initial reign as WBO champion -RRB- , behind Joe Louis -LRB- 25 -RRB- and ahead of Larry Holmes -LRB- 20 -RRB- and Muhammad Ali -LRB- 19 -RRB- . On 14 September 2015 , BoxRec rated Klitschko as the number one fighter in the world , pound for pound . On 15 November 2014 , he reached a career peak of number two on The Rings pound for pound list . Klitschko has fought in 29 heavyweight title fights , more than any heavyweight champion in the sport 's history . He also holds the record of having defeated the most boxers with an undefeated record , at 12 , and has also defeated ten current or former world champions throughout his career .   Wladimir 's older brother , Vitali Klitschko , is also a former WBC , WBO , and The Ring heavyweight champion . From 2006 until 2015 , Wladimir and Vitali dominated heavyweight boxing , a period typically known as the `` Klitschko Era '' of the division .