The Gaiety Theatre was a West End theatre in London, located on Aldwych at the eastern end of the Strand. The theatre was first established as the Strand Musick Hall in 1864 on the former site of the Lyceum Theatre. In 1868, it became known as the Gaiety Theatre and was, at first, known for music hall and then for musical burlesque, pantomime and operetta performances. From 1868 to the 1890s, it had a major influence on the development of modern musical comedy.

Music hall is a type of British theatrical entertainment that was most popular from the early Victorian era, beginning around 1850, through the Great War. It faded away after 1918 as the halls rebranded their entertainment as variety. Perceptions of a distinction in Britain between bold and scandalous music hall entertainment and subsequent, more respectable variety entertainment differ. Music hall involved a mixture of popular songs, comedy, speciality acts, and variety entertainment. The term is derived from a type of theatre or venue in which such entertainment took place. In North America vaudeville was in some ways analogous to British music hall, featuring rousing songs and comic acts.