The London Coliseum (also known as the Coliseum Theatre) is a theatre in St Martin's Lane, Westminster, built as one of London's largest and most luxurious family variety theatres. Opened on 24 December 1904 as the London Coliseum Theatre of Varieties, it was designed by the architect Frank Matcham for the impresario Oswald Stoll. Their ambition was to build the largest and finest music hall, described as the "people's palace of entertainment" of its age.

At the time of construction, the Coliseum was one of the few theatres in Europe to provide lifts for taking patrons to the upper levels of the house, and was the first theatre in England to have a triple revolve installed on its stage. The theatre has 2,359 seats making it the largest theatre in London.

After being used for variety shows, musical comedies, and stage plays for many years, then as a cinema screening films in the Cinerama format between 1963 and 1968, the Sadler's Wells Opera Company moved into the building in 1968. The Sadler's Wells company changed its name to the English National Opera in 1974 and today it is used primarily for opera as well as being the London home of the English National Ballet.

The London Coliseum was built by the architect Frank Matcham who intended it to be one of London's largest and most luxurious family variety theatres. Construction began in 1903 and the venue opened on 24 December the following year as the London Coliseum Theatre of Varieties. It is located in St Martin's Lane, London.

Matcham built the theatre for the theatrical impresario Sir Oswald Stoll and had the ambition of it being the largest and finest "people's palace of entertainment" of the age.

Matcham wanted a theatre of variety – not a music hall but equally not highbrow entertainment. The resulting programme was a mix of music hall and variety theatre, with one act – a full scale revolving chariot race – requiring the stage to revolve. The theatre's original slogan was pro bono publico ('for the public good'). It was opened in 1904 and the inaugural performance was a variety bill on 24 December that year.

English Heritage, in its description of the theatre when it was given listed status in 1960 notes that it is an "exuberant Free Baroque ambitious design, the Edwardian 'Theatre de Luxe of London' with richly decorated interiors and a vast and grandiose auditorium." The theatre has a "lavish foyer and circulation areas with marble facings, culminating in vast 3-tier auditorium with wealth of eclectic classical detail of Byzantine opulence, some motifs such as the squat columns dividing the lowest tier of slip boxes, backing the stalls, almost Sullivanesque; pairs of 2-tiered bow fronted boxes with domed canopies at gallery level and semi-domed, Ionic-columned pairs of 2 tiered orchestra boxes, contained in arched and pedimented frames surmounted by sculptural groups with lion-drawn chariots. Great, semi-circular, blocked architrave proscenium arch with cartouche-trophy keystone."

The inaugural performance was a variety bill on 24 December 1904, but it "was a total failure and closed down completely only two years after opening in 1906 and remained closed until December of 1907 when it was reopened and at last became successful." In 1908, the London Coliseum was host to a cricket match between Middlesex and Surrey. In 1911, dramatist W. S. Gilbert produced his last play here, The Hooligan.