Douglas Stuart Moore (August 10, 1893 – July 25, 1969) was an American composer, songwriter, organist, pianist, conductor, educator, actor, and author. A composer who mainly wrote works with an American subject, his music is generally characterized by lyricism in a popular or conservative style which generally eschewed the more experimental progressive trends of musical modernism. Composer Virgil Thomson described Moore as a neoromantic composer who was influenced by American folk music. While several of his works enjoyed popularity during his lifetime, only his folk opera The Ballad of Baby Doe (1956) has remained well known into the 21st century.

Moore first created music while a student at Yale University from 1911 through 1917; writing usually humorous songs in a popular style for school events in addition to creating music for school plays and musical revues. His work composing music for the Yale Dramatic Association, Elizabethan Club, and Yale Glee Club drew the attention of Yale music department chair Horatio Parker, who persuaded Moore, then a philosophy major, to pursue a second degree in music composition. After completing that degree in 1917, he served as an officer in the United States Navy during World War I before pursuing graduate studies in music composition with Vincent d'Indy at the Schola Cantorum de Paris (1919–1921) and with Ernest Bloch at the Cleveland Institute of Music (1921–1922).

Moore began his professional life as the organist and music director for the Cleveland Museum of Art (CMA) from 1921 through 1925; during which time he also worked professionally as a leading actor with the Cleveland Play House. His first composition of note, Four Museum Pieces, was originally written for organ in 1922 with its four movements named for works of art in the collection of the CMA. Like many of Moore's compositions, this piece was composed during a summer residency at the MacDowell Colony, an artistic summer residency program which Moore attended for many years; first as a fellow and later as a member of the governing board. Moore arranged the work for orchestra at the MacDowell Colony in 1923, and conducted its world premiere with the Cleveland Orchestra that year. The piece won him a competitive Joseph Pulitzer National Traveling Scholarship which funded further composition studies with Nadia Boulanger in Paris in 1926.

In the fall of 1926 Moore joined the music faculty of Barnard College at Columbia University; beginning a lengthy professional career at Columbia. He was rapidly promoted at Columbia from adjunct faculty to professor and head of the music department at Barnard College in 1927; thanks in large part to the success of his orchestral suite The Pageant of P.T. Barnum (composed 1924, premiered 1926) which won the Eastman School of Music composing competition in 1927 and became Moore's first work to be widely programmed in the United States. Moore was director of the Columbia University orchestra from 1926 through 1935. In 1940 he succeeded Daniel Gregory Mason as chair of the music program at Columbia; a post he held until his retirement in 1962. His roles at Columbia and the MacDowell Colony as well as leadership roles on the governing boards of the American Society of Composers, Authors and Publishers and the American Academy of Arts and Letters made Moore one of the more influential music educators of the mid 20th century.

Moore composed music for the theater, film, ballet and orchestra. During his lifetime he was primarily known for his folk operas, beginning with the children's opera The Headless Horseman (1936) which was widely performed at high schools and colleges throughout the United States during the mid 20th century. His next folk opera to achieve success was The Devil and Daniel Webster which premiered on Broadway in 1939 and was based on the 1936 short story of the same name by Pulitizer Prize winning poet Stephen Vincent Benét. Benét was a close friend of Moore's from Yale, and prior to this opera Moore had already composed several art songs to poems by Benét. Benét served as the opera's librettist, and the work went on to enjoy many stagings by American and European opera companies and at universities and conservatories during the 20th century. Moore's Symphony No. 2 in A major (1945) was composed in memory of Stephen Vincent Benét who died in 1943 at the age of 44.

Moore was awarded the Pulitzer Prize for Music for the opera Giants in the Earth in 1951. His best known work, The Ballad of Baby Doe, premiered at the Central City Opera in 1956 and received a critically lauded production at the New York City Opera (NYCO) in 1958. The NYCO recorded the opera with Beverly Sills in the title role. It has remained a part of the standard opera repertory. As an author he penned two books on music, Listening to Music (1932) and From Madrigal to Modern Music (1942).