Theodore Baker (born June 3, 1851, New York, N.Y., U.S.—died Oct. 13, 1934, Dresden, Ger.) was an American music scholar and lexicographer.

Trained as a young man for business, Baker preferred to study music and went to Germany in 1874 for that purpose. He became a pupil of Oskar Paul at the University of Leipzig and received his Ph.D. there in 1882. His dissertation, based on field research among the Seneca Indians in New York, was the first serious study of American Indian music and provided themes for Edward MacDowell’s Second (Indian) Suite for Orchestra.

Baker lived in Germany until 1890, returning to the United States the following year and becoming (1892) the literary editor and translator for the publishing house of G. Schirmer, Inc. He remained at Schirmer until his retirement in 1926, when he returned again to Germany.

In addition to his many English translations of books, librettos, and articles (especially those appearing in the Musical Quarterly, a Schirmer publication), Baker compiled a useful and popular Dictionary of Musical Terms (1895) and Baker’s Biographical Dictionary of Musicians (1900), the work for which he is best known. This last volume included the names of many musicians never previously mentioned in musical reference works. A second edition was published in 1905, and the dictionary underwent several revisions, the 8th edition being published in 1992.