Soviet and Swiss citizen Viktor Lvovich Korchnoi was born on 23 March 1931 in Leningrad. His father taught him to play chess when he was seven years old. His peak World Ranking was 1st (between September and December 1965). He was considered to be one of the ten best chess players of the world between 1959 and 1983. His peak rating was 2814 according to Chessmetrics. His current rating is 2499 (from November 2012).

He was World Championship candidate in 1963, and from 1969 to 1978. He played two World Championship matches, both times against Anatoly Karpov. Karpov won both matches in 1978 by 6-5 and in 1981 by 6-2, defending his title two times against Korchnoi.

Even though he did not win World Champion title, at the age of 75 in 2006 he won the World Senior Chess Championship.  He won 9 points out of 11 games. He is the oldest chess player who won the World Senior Chess Champion title.

He participated in 17 Chess Olympiads between 1960 and 2008, six times competing for the Soviet Union and eleven times representing Switzerland. As a member of the Soviet team he won team gold medal in all events (in 1960, 1966, 1968, 1970, 1972 and 1974) and he won three individual gold and bronze medals. As a member of the Swiss team he won an individual gold medal in 1978 (Wikipedia).

Interesting facts:

He was awarded with Chess Oscar in 1978.

In 1972 together with Grandmasters Tal, Averbah, Tajmanov and Kotov he took a role in the movie “Grandmaster” (Lenfilm, directed by Sergei Mikazljan) in which he played a grandmaster, trainer of the main character. After his defection to Switzerland the movie was not shown any more in the Soviet Union.

Partially his defection to Switzerland in 1976 inspired the musical “Chess”.