Louis Achille Hirsch, also known as Louis A. Hirsch and Lou Hirsch, was an American composer born on November 28, 1887, in New York City. He was a prominent figure in the early 20th century music scene, known for his contributions to songs and musicals. Hirsch studied piano at Berlin's Stern Conservatory under Rafael Joseffy and returned to the United States in 1906, where he began his career as a staff pianist in Tin Pan Alley.

Hirsch's early work involved writing music for Lew Dockstader's Minstrels and contributing melodies to Broadway shows such as The Gay White Way and Miss Innocence. His first full score was for He Came From Milwaukee in 1910. He gained significant recognition with the Revue of Revues in 1911, which introduced French star Gaby Deslys to America. His collaboration with Deslys led to popular songs like "The Gaby Glide."

One of Hirsch's major successes was Vera Violetta in 1911, which helped launch Al Jolson's career. He worked with the Schuberts on productions like The Whirl of Society and The Passing Show. Hirsch was a founding member of ASCAP in 1914 and served as a director from 1917 to 1924. During World War I, he contributed to The Ziegfeld Follies and wrote music for musicals such as Oh, My Dear! and Going Up, the latter featuring his hit song "Love Nest."

Hirsch's other notable works include The Rainbow Girl, See Saw, and The O'Brien Girl. He was known for both his musical compositions and his role in developing storylines for musicals. Tragically, Louis Hirsch died of pneumonia on May 13, 1924, in New York City at the age of 36.