Horatio William Parker (1863–1919) was an American composer and conductor, recognized primarily for his contributions to classical music, particularly in the realm of opera and choral works. A notable figure in the development of American classical music, Parker was influenced by the European tradition, having studied at Yale and later in Germany. His most significant works include the opera "Mona," which premiered in 1910 and was one of the first operas by an American composer to be performed at the Metropolitan Opera. Other notable compositions include the oratorio "The Last Judgment" and various choral works that showcase his lyrical style and rich harmonies. Parker's music is characterized by its blend of Romantic sensibilities with American themes, reflecting a growing national identity in classical music during his time. Parker's impact on music extends beyond his compositions; he was a mentor to many young musicians and played a pivotal role in promoting American music through his teaching and conducting. His work laid important groundwork for future American composers and contributed to the establishment of a distinct American voice in classical music.