The World Boxing Organization (WBO) is a sanctioning organization currently recognizing professional boxing world champions. The organization is recognized as one of the four major world championship groups by the IBHOF alongside the International Boxing Federation, the World Boxing Council and the World Boxing Association. WBO offices are located in San Juan, Puerto Rico.

The WBO started after a group of Puerto Rican and Dominican businessmen broke out of the World Boxing Association's 1988 annual convention in Isla Margarita, Venezuela over disputes regarding what rules should be applied.

The WBO's first president was Ramon Pina Acevedo of the Dominican Republic. Soon after its beginning, the WBO was staging world championship bouts around the globe. Its first championship fight was for its vacant super middleweight title, between Thomas Hearns and James Kinchen; Hearns won by decision. In order to gain respectability, the WBO next elected former world light heavyweight champion José Torres of Ponce, Puerto Rico, as its president. Torres left in 1996, giving way to Puerto Rican lawyer Francisco Varcarcel as president. Varcarcel has been there since.

Ricky Burns (born 13 April 1983) is a Scottish boxer from Coatbridge who fights in the lightweight division and is currently the WBO lightweight champion after Juan Manuel Marquez vacated his belt and moved up to light welterweight. He is also a former WBO Super-Featherweight champion, Commonwealth super featherweight champion and has previously challenged for both the British and European titles.

Burns first fight as a professional was a four round victory in October 2001 over Woody Greenaway at the Kelvin Hall in Glasgow. On 12 December 2004, following a string of seven wins over opponents including Jeff Thomas, Ernie Smith and Daniel Thorpe he was matched against fellow unbeaten prospect Colin Bain. The fight, at the Marriott Hotel in Glasgow, resulted in a first career defeat for Bain as Burns won over the six round distance. For Burns, the win set him up for a journey south of the border to face the unbeaten British lightweight champion Graham Earl in a non-title fight. The fight with Earl took place at the Wembley Conference Center and Burns produced one of the upsets of the year when he scored a points victory to beat Earl over eight rounds.

David Deron Haye (born 13 October 1980) is a British professional boxer from England.

Haye is the former WBA heavyweight champion. He is also the former unified world cruiserweight champion, holding the WBA, WBC, WBO, and The Ring cruiserweight titles, and the former European cruiserweight champion.

Haye started his ambition and passion for boxing at old-school boxing gym Fitzroy Lodge Boxing Club in Lambeth, South London, where he quickly impressed and confidently won his first amateur bouts.

In 1999, 18-year-old Haye participated at the world amateur championships in Houston, Texas, USA at light-heavyweight but was eliminated by experienced American Michael Simms early in the contest.

At the 2001 World Amateur Boxing Championships in Belfast, Northern Ireland he fought in the heavyweight 201 lb division where he beat world class Sebastian Köber to reach the final where he gave Odlanier Solís a standing eight count before being stopped by the Cuban in round three, and taking the silver medal.

Enzo Maccarinelli (born 20 August 1980 in Swansea, Wales) is a Welsh professional boxer who has fought at Cruiserweight and light heavyweight. He is a former World Boxing Organization (WBO) cruiserweight title holder and also held the European title at that weight limit. He is promoted by Frank Warren.

On 12 May 2000, Maccarinelli suffered his first defeat at the hands of southpaw Lee Swaby. Swaby, from Lincoln, England, sent Maccarinelli down with a crushing right hand, knocking Maccarinelli down in the third round. Maccarinelli never took the rematch against Swaby.

On 28 June 2003, Maccarinelli, known as "the Big Mac" won the vacant WBU cruiserweight title when he defeated Bruce Scott by fourth-round TKO. He made seven successful defences of his WBU title before vacating.

On 8 July 2006, Maccarinelli fought against former World Boxing Council (WBC) cruiserweight champion Marcelo Fabian Domínguez for the WBO interim cruiserweight title. Maccarinelli won the title with a ninth-round TKO.The natural progression was a title fight against the then WBO title holder, Johnny Nelson. Due to several injuries to Nelson this matchup never transpired, and On 22 September 2006 he announced his retirement, automatically relinquishing the belt and allowing Maccarinelli to be promoted to full champion status.

Wladimir Klitschko (Ukrainian: Володи́мир Володи́мирович Кличко́ [transliteration: Volodymyr Volodymyrovych Klychko], born 25 March 1976) is a Ukrainian heavyweight professional boxer. Klitschko is the WBA (Super), IBF, WBO, IBO & The Ring Heavyweight Champion. His older brother Vitali Klitschko is the current WBC Heavyweight Champion. Klitschko is the longest reigning Heavyweight Champion in history for the IBF, WBO & IBO Heavyweight titles, both in measurements of defenses and time & overall the 6th longest reigning Heavyweight Champion of all time. As of 2011, Boxrec rates Klitschko as the number 2 pound-for-pound in the world. Ring Magazine currently rates Klitschko as the number six pound-for-pound boxer in the world.

Since 2005, Klitschko has been the dominant force in the heavyweight division, defeating a majority of the top heavyweights in the rankings. When Klitschko won the IBF title against Chris Byrd there were four separate Heavyweight Champions. Since then, he has unified the IBF, IBO, WBO & WBA belts and defeated the WBA Champion in recess. Following his win over Ruslan Chagaev, Klitschko was awarded the vacant Ring Magazine Heavyweight title.