Leopold Auer (born June 7, 1845, Veszprém, Hungary—died July 15, 1930, Loschwitz, near Dresden, Germany) was a Hungarian-American violinist especially renowned as a teacher, who numbered among his pupils such famous performers as Mischa Elman, Jascha Heifetz, Efrem Zimbalist, and Nathan Milstein.

Auer studied under the celebrated virtuoso Joseph Joachim. From 1868 he was professor of violin at the St. Petersburg Conservatory in Russia and in 1883 became a Russian subject. While living in St. Petersburg he also taught in London and in Dresden, Germany. In 1918 he settled in New York City. Pyotr Ilyich Tchaikovsky originally dedicated his violin concerto to Auer, but, disappointed that Auer regarded the work as unplayable, he changed the dedication. Later Auer changed his mind about the piece, and thereafter the concerto occupied a prominent place in his extensive repertory. He wrote Violin Playing As I Teach It (1921), My Long Life in Music (1923), and Violin Master Works and Their Interpretation (1925).