Yakov Izrailevich Zak (Ukrainian: Яків Ізраїлович Зак), (Russian: Яков Израилевич Зак), Jiakov Israilevič Sak; Odessa, 20 November [O.S. 7 November] 1913 – Moscow, 28 June 1976) was a Soviet pianist and teacher of Jewish extraction.
Born in Odessa, Zak studied piano at the Odessa Conservatory with Maria Starkhova, took classes on special harmony with Mykola Vilinsky, and later studied with Heinrich Neuhaus in Moscow, graduating in 1935. Having made his debut in 1935, he rose to prominence when he won First Prize and the Mazurka Prize at the International Frederick Chopin Piano Competition in 1937. From 1935 Zak taught at the Moscow Conservatory, becoming a professor in 1947 and being granted a chair in 1965. His pupils include Irina Zaritskaya, Nikolai Petrov, Evgeny Mogilevsky, Lubov Timofeyeva, Valery Afanassiev, Ludmila Knezkova-Hussey and Youri Egorov. In 1966 Yakov Zak was made People's Artist of the USSR.