Leo Mittler (1893–1958) was an Austrian playwright, screenwriter and film director. Mittler was born in Vienna, then the capital of the Austro-Hungarian Empire, to a Jewish family. He attended the University of Music and Performing Arts and worked as a playwright and director in the German theatre. Mittler then switched to work in the booming German film industry during the silent era.
Mittler's best known film as director was Beyond the Street (1929), a "street film" influenced by Soviet cinema. As well as his work in the German industry, Mittler also spent time at the American company Paramount's French language-subsidiary based at the Joinville Studios in Paris.
Following the Nazi rise to power in 1933, Mittler spent many years in exile in several countries including Britain and France before settling in the United States during the Second World War. Mittler's career as a director had all but ended in the mid-1930s, after making the Stanley Lupino musical comedy Cheer Up (1936), but he worked occasionally as a screenwriter.
Mittler wrote the original story of the MGM pro-Soviet film Song of Russia (1944) which was later investigated by HUAC for its alleged communist sympathies. Mittler returned to Germany post-war, and died there in 1958. Before his death, he worked for German theatre and television.