(born 1943), U.S. chess master, born in Chicago, Ill.; in 1958 became world's youngest player ever ranked grand master; from 1958 to 1972 won many U.S. championships and World Championship Candidate matches; in 1972 was first American to become Chess Champion of the World; retained World title until 1975, when he forfeited it by refusing a challenge to play Soviet Anatoly Karpov; in 1992 beat Boris Spassky in “5-million-dollar match” in war-torn Yugoslavia; noted for aggressive use of surprise attacks and counterattacks; became notorious for demands that numerous conditions be met for play.