Louis Alter (June 18, 1902 – November 3, 1980) was an American pianist, songwriter, and composer renowned for his contributions to film, Broadway, and popular music. Born in Haverhill, Massachusetts, Alter began his musical career at the age of 13 by playing piano in theaters for silent films. He studied at the New England Conservatory of Music under Stuart Mason.

Alter's early career included performing in vaudeville, where he accompanied notable headliners such as Irène Bordoni and Nora Bayes, touring extensively until Bayes' death in 1928. This experience led him to focus on songwriting, resulting in his first hit, "Manhattan Serenade" (1929), which became widely recognized and was later featured in the Easy Aces radio program.

In 1929, Alter transitioned to Hollywood, where he wrote songs for films and continued to accompany singers like Beatrice Lillie and Helen Morgan. His Broadway contributions included songs for musicals such as "Sweet and Low" (1930) and "Ballyhoo" (1931). Among his popular compositions are "My Kinda Love," "You Turned the Tables on Me," and "Do You Know What It Means to Miss New Orleans," the latter written for the 1947 film "New Orleans."

During World War II, Alter served with the United States Air Force, entertaining troops and coordinating shows at West Coast air bases. He also performed as a piano soloist with the Los Angeles Philharmonic at the Hollywood Bowl. Alter composed large-scale works for piano and orchestra, including "American Serenade" and "Metropolitan Nocturne."

Alter was twice nominated for Academy Awards for his songs "Dolores" and "A Melody from the Sky" and was inducted into the Songwriters Hall of Fame in 1975. He spent his later years living in New York City and maintained a summer residence on Fire Island. Louis Alter passed away from pneumonia on November 3, 1980, in Manhattan, New York City.