Veselin Topalov

Veselin Topalov (Веселин Топалов, born 15 March 1975), is a Bulgarian chess grandmaster and former 'FIDE world chess champion'. This was a knock-out tournament of lower status than the classical world championship. 
Topalov became the FIDE champion in 2005. He lost his title in a classical match against Vladimir Kramnik, the purpose of which was to unify the titles. During the match, his manager accused his opponent of cheating. The match ended the division between world titles, which had arisen in 1993. Next, Topalov defeated Gata Kamsky in February 2009 in Sofia, Bulgaria to earn the right to be the challenger for the World Chess Championship in 2010. Topalov lost the World Championship match with Anand 5½–6½ in May 2010.
Topalov won the 2005 Chess Oscar. He was ranked #1 in the world from April 2006 to January 2007, and then had the second highest Elo rating of all time (2813). He regained the world #1 ranking again in October 2008, and officially remained #1 until January 2010, when he fell to #2 behind Magnus Carlsen. 
He has been ranked number one a total of 27 months in his career, the fourth longest, behind only Garry Kasparov, Anatoly Karpov, and Bobby Fischer.