Sidney Foster (May 23, 1917 — February 7, 1977), born Sidney Earl Finkelstein, was an American virtuoso pianist and teacher. He studied with Isabelle Vengerova and David Saperton at the Curtis Institute of Music in Philadelphia, and in 1940 became the first winner of the Edgar M. Leventritt Award. He was described as "an interesting, original pianist, the master of tonal shading and an artist."
Sidney Foster was born in Florence, South Carolina, in 1917, the son of Louis Finkelstein, a jeweler and pawnbroker, and Anna Diamond. In 1925 he moved to Miami, Florida and had piano lessons with Earl Chester Smith. After playing for pianist Josef Hofmann, then Director of the Curtis Institute, he was accepted as one of the youngest pupils ever of that celebrated institution. He was first assigned to the class of Isabelle Vengerova and later to American pianist David Saperton, the son-in-law of pianist Leopold Godowsky. In October 1939 he married Bronja Singer, a fellow student of Saperton's at the Curtis Institute. The couple had two sons, Lincoln and Justin.
In 1938, Foster won the Mac Dowell Competition, and in October 1940 his winning of the Edgar M. Leventritt Prize led to his debut with the New York Philharmonic Orchestra at Carnegie Hall under John Barbirolli. For his debut, Foster played Beethoven's C Minor Concerto, and composed his own first movement cadenza. His appearance was hailed by The New York Times with the headline "Ovation to Sidney Foster", and was described as "a reading in the grand manner".
In 1941, Foster founded a flute, piano and cello trio with French flutist René Le Roy and Hungarian cellist Janos Scholz, and composed a few works for the ensemble that were performed at their Town Hall concerts. At the same time he embarked on a busy concert schedule, with yearly appearances in recital at Carnegie Hall that were enthusiastically received as "interpretations (of) sweep and power" by "an artist of high rank." Foster toured Japan in 1962, playing recitals, concerti with orchestra, and chamber music with violinist Toshiya Eto. In November 1964 he toured the Soviet Union, playing sixteen concerts in twenty-two days. In the United States he played as soloist with the New York Philharmonic at Lewisohn Stadium and at the Watergate Barge Concerts in Washington, D.C., the Minneapolis Symphony under Dimitri Mitropoulos, the Chicago Symphony at Ravinia under William Steinberg, the Boston Symphony under Aaron Copland, the Dallas Symphony under Jacques Singer, the Indianapolis Symphony under Izler Solomon, and the Utah Symphony under Maurice Abravanel.