Leo Spies (4 June 1899 – 1 May 1965) was a Russian-born German composer and conductor active in the musical and theatrical life of Germany, and especially in Berlin.
Spies was born in Moscow and was educated there before his family emigrated to Dresden where he trained with Johannes Schreyer and Oskar von Riesemann. He then studied at the Berlin Hochschule für Musik under Engelbert Humperdinck and Robert Kahn from 1916 to 1917. In his early career he worked as a repetiteur in various German theatres and for Universum Film AG. During the late 1920s, he became involved with Hanns Eisler's circle and the workers' choral movement for which he composed several choral works. He was the ballet conductor of the Berlin State Opera from 1928 to 1935 and the Deutsche Opernhaus from 1935 to 1944. He then served as director of studies and conductor at the Komische Oper from 1947 to 1954.
As a composer, Spies's work was influenced by Russian romanticism and the works of Janáček. He composed in virtually all the classical genres: ballets, concertos, symphonies, chamber music, piano sonatas, lieder, and choral music. His principal ballet works are Apollo und Daphne (1936), Der Stralauer Fischzug (1936), Seefahrt (1937), Die Sonne lacht (1942), Pastorale (1943), Die Liebenden von Verona (1944), and Don Quijote (1944). He also composed incidental music for plays, including the 1946 Berlin production of Zum goldenen Anker (the German language adaptation of Marcel Pagnol's Trilogie marseillaise).