Alexander Kazimirovich Tolush (March 1, 1910 – March 3, 1969) was a Soviet chess player and trainer. He won the Leningrad Championship in 1937, 1938, and 1946. He also participated in eight USSR Championships, with his best result being third place in 1950. Tolush played several well-reviewed games against leading players such as world champions Botvinnik and Smyslov. He was awarded the title of International Master in 1950 and the Grandmaster title in 1953 by FIDE, the international chess federation.
From 1943 to 1969, Tolush served as coach to several prominent Soviet chess players including Boris Spassky, whom he guided to the World Championship in 1969. Alexander Tolush was awarded the title 'Honored Coach of USSR' in 1964.
Tolush's playing style was aggressive, which resulted in sharp, complex positions. However, his style limited his success in tournaments, as it took more time than usual to come up with accurate aggressive plans, leading to time pressure and faults.
Tolush's personal life was turbulent; he was reportedly physically abusive towards his wife, fellow chess player Valentina Borisenko. Tolush himself was an alcoholic. Despite being remembered as a strong player and influential coach, he lived in relative poverty. He died suddenly of a heart attack in 1969.
Alexander Tolush is credited for the development of an aggressive line in the King's Gambit Accepted, known as the "Tolush–Geller Gambit". This has been popular among attacking players and is still used in top-level competition.