The Mercury Theatre was an Australian theatre company that was co-founded by Peter Finch and existed from 1946–1954. It was named after Orson Welles' theatre company of the same name.
The Mercury was founded in 1946 by Finch, Allan Ashbolt, Sydney John Kay, Colin Scrimgeour and John Wiltshire. The driving force for much of the company's time was Kay. They would frequently tour shows throughout the country.
The Mercury is best known for its production of The Imaginary Invalid starring Finch on the floor of O'Brien's Glass Factory in Sydney in 1948; this was seen by Laurence Olivier and Vivien Leigh who were so impressed they invited Finch to come to London. Kay revived the company in 1952, and it ran for the next two years from a base at St James' Hall in Sydney. Among those who acted in Mercury shows over the years included Rod Taylor, Ruth Cracknell and Lloyd Berrell.