Viktor Korchnoi (23 March 1931 – 6 June 2016) was a professional chess grandmaster. He was born in Leningrad, USSR (Saint Petersburg). In 1976 he defected to the Netherlands. He lived in Switzerland for many years, and became a Swiss citizen. Towards the end of his life, he was the oldest active grandmaster on the regular tournament circuit. Viktor was at or near the top in chess for half a century.