List of World Chess Championships

The World Chess Championship has taken various forms over time, including both match and tournament play. While the concept of a world champion of chess had already existed for decades, with several events considered by some to have established the world's foremost player, an event explicitly held to decide a world champion did not take place until 1886. World Championships were initially privately organized matches, with each requiring the consent of the incumbent champion in order to take place. After 1948, the International Chess Federation (FIDE) began organizing the Championship under its auspices. The championship was fixed to a three-year cycle, with each challenger decided by a Candidates Tournament. In 1993, the short-lived Professional Chess Association (PCA) split from FIDE, and as a result there were two competing World Championship titles between 1993 and 2006.

Predecessor events (before 1886)
Chess was first introduced to Europe during the 9th century. In the early modern era, following the solidification of the modern rules of chess, the game continued to carry consistent prestige and public interest. While numerous players have been characterized as the game's strongest over the centuries, the idea of an international chess match or tournament did not occur until the 18th century, and did not materialize until the 19th century. While the following events did not have the title of World Champion at stake, they have been recognized—either at the time or in retrospect—as indicating the world's leading player.

Privately organized matches (1886–1946)
With both Wilhelm Steinitz and Johannes Zukertort seen as plausible claimants, the two played a match for the first World Championship in 1886. While Steinitz would later claim that he had been the World Champion since the 1860s, no match before 1886 was played for any formal title. From then until after World War II, championship matches were privately organized, and the champion was not formally obliged to face an opponent. An agreement had to be reached between the champion, the challenger, and the patrons sponsoring each match, which included providing the funds for the prize pool. Lasker's 27-year reign as World Champion is the longest in the history of organized chess since 1886, but featured two separate 10-year spans during which he did not defend his title.

FIDE World Championships (1948–1990)
In 1946, Alexander Alekhine died while still holding the title of World Chess Champion. The International Chess Federation (FIDE), which had been founded in 1924, had been attempting to directly participate in organizing the World Championship since at least 1935. By the late 1940s, around half of the plausible contenders for the World Championship were Soviet citizens, and in 1947, the Soviet Chess Federation joined FIDE after decades of declining to do so. FIDE based the 1948 World Chess Championship on the 1938 AVRO tournament that had been organized in part to select a challenger for Alekhine. The tournament ultimately featured five players, three of them Soviet citizens—including the winner, Mikhail Botvinnik. Botvinnik would go on to win or retain in four further championship matches. At the same time, FIDE established the rules for the championship going forward. It would be organized around a 3-year cycle, during which a series of Zonal and Interzonal tournaments would be held, with their highest-scoring performers invited to a Candidates Tournament. The winner of the this tournament would in turn play the champion in a match for the title. A defeated champion was entitled to a rematch the following year, after which the 3-year cycle would resume; Botvinnik benefited from this rule twice, in 1958 and 1961.

With the exception of the American Bobby Fischer in 1972, Soviet citizens won every championship from 1948 until the dissolution of the Soviet Union in 1991. With the further exception of Viktor Korchnoi, who had defected from the USSR in 1976, each challenger was also a Soviet citizen. Following his victory, Fischer never played another game organized by FIDE. Disagreements between the two parties—including Fischer insisting on a format requiring the victor to get a certain number of wins, as opposed to the number of games in a match being fixed—led to his forfeiting the title in 1975. In the absence of a match, FIDE declared Anatoly Karpov, winner of the 1974 Candidates Tournament, to be the World Chess Champion by default.

While the issue had played a role in Fischer's forfeit, FIDE ultimately did change the match format going forward, such that the first to win 6 games would be champion. Under these rules, Karpov twice defended his title against Korchnoi. The next match—which began in September 1984 and featured the 21-year-old Garry Kasparov as Karpov's challenger—ultimately saw 48 games played over the span of five months, with neither player able to get to 6 wins. In an unprecedented step, FIDE president Florencio Campomanes stepped in and declared the match to have ended with no result. A new match, which would revert to having a set number of games, was to be played later in 1985. After nearly being knocked out early in 1984, Kasparov defeated Karpov in their rematch. Over the following decade, the two would play three more championship matches, with Kasparov narrowly retaining the title in each.

Split title (1993–2006)
In 1993, following Nigel Short's victory in the Candidates Tournament, FIDE president Campomanes announced that that year's Championship would take place in Manchester, England. Both Kasparov and Short claimed that FIDE had made this decision without consulting either player, in violation of FIDE's regulations regarding the championship. Kasparov and Short responded by splitting from FIDE and forming the Professional Chess Association (PCA), which organized a World Championship match between the two, played in London later that year. Meanwhile, FIDE stripped Kasparov of his title and organized a championship match between Karpov and Jan Timman, who had finished second and third in the Candidates Tournament. For the 13 years between 1993 and 2006, there were two rival titles. While the PCA itself would fold after only a couple of years, Kasparov would retain what is referred to as "Classical" title, which would be inherited by Vladimir Kramnik upon defeating Kasparov in 2000.

Meanwhile, FIDE once again began experimenting with the championship format. Beginning with the 1998 championship, the system of Zonal, Interzonal, Candidates, and Championship stages was replaced with one single-elimination tournament featuring dozens of players competing for the championship. For the next event in 1999, the incumbent World Champion would not automatically qualify for the finals. Due to this additional change, Karpov—who had won three additional titles during the schism—declined to participate going forward. Each of the four Classical Championships retained a traditional match format.

FIDE World Championships (2006–present)
Following a period of negotiation, in 2006 the Classical Champion Vladimir Kramnik played a match against the FIDE Champion Veselin Topalov to reunify the World Championship. Since then, the championship has remained under the auspices of FIDE. The Candidates Tournament returned, and with the exception of the 2007 tournament, FIDE would return to a match format for the World Championship. Instead of the previous system of Zonals and Interzonals to provide candidates, the system was redesigned around the Chess World Cup. Later, means for selecting candidates would variously include the FIDE Grand Prix, the FIDE Grand Swiss Tournament, selection by rating, and wild cards selected by the venue hosting the event.

While shorter matches had taken place at various points, the block of 12 classical games was much shorter than matches had been for much of the 20th century. In the 2018 match, all 12 classical games resulted in draws for the first time in the history of the championship. Following this, the number of games was increased to 14. Citing a lack of motivation and interest in the format, incumbent five-time champion Magnus Carlsen declined to defend his title in 2023. Instead, the match featured the two best performers in the Candidates, with Ding Liren defeating Ian Nepomniachtchi to become the new World Champion. Carlsen later declined his spot in the 2024 Candidates Tournament.

Unrecognized championship events
In 1909, amid discussions that would ultimately culminate with the World Championship match played the following year, Emanuel Lasker played a casual match with Dawid Janowski in Paris. This was reported in later decades as being a World Championship match. However, research by Edward Winter has demonstrated that the title was not at stake.