William Greet was a British theatre manager from the end of the 19th century and into the 20th century. Originally a business manager for other theatre licensees in the 1880s, he branched out as an independent manager in the 1890s and was associated with various London theatres, principally the Lyric, the Savoy and the Adelphi Theatres.

The Lyric Theatre is a West End theatre in Shaftesbury Avenue in the City of Westminster. It was built for the producer Henry Leslie, who financed it from the profits of the light opera hit, Dorothy, which he transferred from its original venue to open the new theatre on 17 December 1888.