Viktor Korchnoi was a Soviet-born and later Swiss chess grandmaster, widely regarded as one of the strongest players never to win the World Chess Championship. His elite career spanned roughly seven decades, combining exceptional longevity with relentless competitiveness and making him one of the most respected figures in chess history.
Korchnoi earned the grandmaster title in 1956 and became one of the Soviet Union's leading players during the 1960s. He won the USSR Chess Championship four times (1960, 1962, 1964–65, and 1970), an extraordinary achievement given the depth of Soviet chess, and qualified for the Candidates on ten occasions between 1962 and 1991.
- World Championship rivalry
Korchnoi came agonizingly close to the world title. He lost the 1974 Candidates Final to Anatoly Karpov, then challenged Karpov for the World Championship in 1978 and 1981 after defecting from the Soviet Union in 1976. The 1978 match in Baguio became one of the most famous in chess history because of its intense psychological battles and off-the-board controversies, with Karpov ultimately prevailing by the narrowest margin.
Known for his fighting style, deep opening preparation, and exceptional defensive technique, Korchnoi remained a world-class competitor well into his seventies. After settling in Switzerland and becoming a Swiss citizen, he added multiple Swiss national titles and won the World Senior Chess Championship in 2006. His remarkable longevity and sustained excellence have cemented his reputation as perhaps the greatest player never to become world champion.