William Steinberg (Cologne, August 1, 1899 – New York City, May 16, 1978) was a German-American conductor.
Steinberg was born Hans Wilhelm Steinberg in Cologne, Germany. He displayed early talent as a violinist, pianist, and composer, conducting his own choral/ orchestral composition (based on texts from Ovid's Metamorphoses) at age 13. In 1914, he began studies at the Cologne Conservatory, where his piano teacher was the Clara Schumann pupil Lazzaro Uzielli and his conducting mentor was Hermann Abendroth. He graduated with distinction, winning the Wüllner Prize for conducting, in 1919. He immediately became a second violinist in the Cologne Opera orchestra, but was dismissed from the position by Otto Klemperer for using his own bowings. He was soon hired by Klemperer as an assistant, and in 1922 conducted Fromental Halévy's La Juive as a substitute. When Klemperer left in 1924, Steinberg served as Principal Conductor. He left a year later, in 1925, for Prague, where he was conductor of the German Theater. He next took the position of music director of the Frankfurt Opera. In 1930, in Frankfurt, he conducted the world premiere of Arnold Schoenberg's Von heute auf morgen.
He was relieved of his post in 1933 by the Third Reich because he was Jewish. According to the grandson of composer , Steinberg was "rehearsing [Toch's opera Der Fächer (The Fan)] in Cologne when Nazi brownshirts came storming into the hall and literally lifted the baton out of his hand".; Steinberg, who had married Lotte Stern in Frankfurt in 1934, was then restricted to conducting concerts for the Jewish Culture League in Frankfurt and Berlin. The Steinbergs left Germany in 1936 for the British Mandate of Palestine, which is now Israel. Eventually, with co-founder Bronisław Huberman, Steinberg trained the Palestine Symphony Orchestra, which would later be known as the Israel Philharmonic Orchestra. Steinberg was conducting the orchestra when Arturo Toscanini visited there in 1936. Toscanini was impressed with Steinberg's preliminary groundwork for his concerts and later engaged him as an assistant in preparing for the NBC Symphony Orchestra radio broadcasts.