Lothar Wallerstein (6 November 1882 – 14 November 1949) was Czech-born musician and conductor of Austrian descent who became a U.S citizen in 1945, four years before his death. He was a stage manager at the Vienna State Opera, Salzburg Festival and Metropolitan Opera. He became stage director of the Vienna State Opera in 1926, where in 1931 he collaborated with Richard Strauss in re-writing Mozart’s "Idomeneo". He emigrated to New York City in 1940 to evade the rise of Nazi influences in Austria, followed by the German annexation of that country, and the subsequent invasion of the Netherlands where he had sought refuge. At the end of World War II, he returned to Europe, where he taught acting classes for singers, and founded an opera school in The Hague, Netherlands.