During the 20th century, London theatres encountered stiff competition from the rise of cinema and, later, television. By the 1930s, London had 142,000 theatre seats as opposed to 344,000 cinema seats. By the end of the century, the number of theatre seats had declined to 60,000. Nevertheless London remained the theatre capital of Britain, with over two-fifths of all those employed in this field working in London, and attendances of over 10 million people annually.
London's significant 20th-century London theatres included many internationally recognised names.
- The Old Vic was established on the South Bank near Waterloo in 1888 by the social reformer Emma Cons. It was taken over in 1912 by her niece Lillian Baylis. Baylis's reign saw the Old Vic become London's leading arts theatre, accommodating the Sadlers Wells ballet and the early form of the National Theatre.
- The Everyman Theatre, Hampstead, was founded in 1919 in an old army hall. It staged the first production of Noel Coward's The Vortex in 1926. In 1933, the Everyman became a cinema.
- The Arts Theatre, Westminster, was founded in 1927 for avant-garde productions. In 1956, it staged the London premiere of Samuel Beckett's Waiting for Godot.
- The Royal Court Theatre, Kensington and Chelsea, was taken over by the English Stage Company under George Devine in 1956. The theatre established a reputation for innovative drama. John Osborne's Look back in Anger was one of the company's first productions in 1956.
- The Theatre Royal, Stratford, was taken over by the Theatre Workshop under Joan Littlewood in 1953. It had a strong social mission to bring theatre to East Enders. Its most famous production was Oh What a Lovely War, which opened in 1963.
- The Mermaid, Blackfriars, was the initiative of actor Sir Bernard Miles. The Mermaid opened in 1959 in a converted Victorian warehouse. It was the first new theatre to be built in the City of London for 300 years.
- The National Theatre, Southwark, opened in 1976 as part of the South Bank arts complex, designed by Denys Lasdun. The building had three different stages to accommodate different forms of drama. The first production in March 1976 was Hamlet, starring Albert Finney in the title role.
- The Barbican Theatre, City of London, opened in 1981 as part of the Barbican arts complex. From 1982, it was the London home of the Royal Shakespeare Company.
- The Globe, Southwark, was built on the initiative of American actor Sam Wannamaker. The Globe was a full-scale reconstruction of an Elizabethan theatre designed to stage Shakespeare plays in authentic settings. It opened in 1994.
