William Greet (1851 – 25 April 1914) 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.