Louise Beatty Homer (April 30, 1871 – May 6, 1947) was an American operatic dramatic contralto who had an active international career in concert halls and opera houses from 1895 until her retirement in 1932.

After a brief stint as a vaudeville entertainer in New England, she made her professional opera debut in France in 1898. She then became a member of the Metropolitan Opera from 1900 to 1919 and again from 1927 to 1929. She was also active as an opera singer in Boston, Chicago, and California. She recorded extensively for Victor Records and Columbia Records in the early decades of the 20th century. She was married to composer Sidney Homer for 52 years. The composer Samuel Barber was her nephew.

Homer sang a broad repertoire which encompassed works from the French, German, and Italian repertoires. She enjoyed particular success in the operas of Giuseppe Verdi and Richard Wagner. She often stated in interviews that her favorite role to perform was Amneris in Verdi's Aida. At the Met she sang in several United States premieres and created roles in two world premieres: the witch in Engelbert Humperdinck's Königskinder and the title role in Horatio Parker's Mona. Soprano Nellie Melba once hailed her as "the world's most beautiful voice". In 1923 and 1924 she was listed as one of the 12 greatest living women by the National League of Women Voters.