Viktor Korchnoi

Viktor Korchnoi was arguably the strongest player never to become world chess champion. He is best known for the three World Championship matches he played with Anatoly Karpov in 1974, 1978 and 1981—losing the first two by only a single game. The last two matches were played after he defected from the Soviet Union in 1976. A candidate for the World Chess Championship on ten occasions (1962, 1968, 1971, 1974, 1977, 1980, 1983, 1985, 1988, 1991), no player in the history of the game has played so well for as long as Korchnoi, who remained a world-class player into his late 70s.