Dame Janet Abbott Baker (born 21 August 1933) is an English mezzo-soprano best known as an opera, concert, and lieder singer.

Baker is particularly closely associated with baroque and early Italian opera and the works of Benjamin Britten. During her career, which lasted from the 1950s to the 1980s, she was considered an outstanding singing actress and widely admired for her dramatic intensity, perhaps best represented in her famous portrayal as Dido, the tragic heroine of Berlioz's magnum opus, Les Troyens. As a concert performer, Baker was noted for her interpretations of the music of Gustav Mahler and Edward Elgar. David Gutman, writing in Gramophone, described her performance of Mahler's Kindertotenlieder as "intimate, almost self-communing".