Oscar George Theodore Sonneck (October 6, 1873 in Jersey City – October 30, 1928 in New York) was a U.S. librarian, editor, and musicologist.
Sonneck studied philosophy and musicology in Germany at the universities of Heidelberg and Munich.
From 1902 to 1917, he was head of the music division of the Library of Congress, and as such created a significant music library. Since 1915, he was also editor of the The Musical Quarterly. As a writer, he specialized in the history of early (before the 19th century) American music.
The Society for American Music was created in his honor, and initially named after him.
