Marianne Phoebe Elliott OBE (born 27 December 1966) is a British theatre director and producer who works on the West End and Broadway.

She has received critical and box-office success directing original West End productions of War Horse in 2007 and The Curious Incident of the Dog in the Night-Time in 2012, as well as revivals of Tony Kushner's Angels in America in 2017, Stephen Sondheim's musical Company in 2018, and Arthur Miller's Death of a Salesman in 2019, all of which transferred to Broadway.

Elliott was appointed Officer of the Order of the British Empire (OBE) in Queen Elizabeth II's 2018 Birthday Honours for services to theatre.

"[4] After leaving university Elliott was, initially, determined not to go into the theatre and had a number of different jobs including casting director and drama secretary at Granada Television.

During this time, Elliott's productions included Notes on Falling Leaves by Ayub Khan Din, The Sugar Syndrome by Lucy Prebble, Stoning Mary by Debbie Tucker Green and Local as well as many new writing workshops and play readings.

[4] She became an associate director under Hytner, and directed a series of important, influential and highly successful productions including War Horse and The Curious Incident of the Dog in the Night-Time.

Its first production was the West End premiere of Heisenberg by Simon Stephens, directed by Elliott at the Wyndham's Theatre (3 October 2017 – 6 January 2018) which garnered mixed reviews and poor houses; an inauspicious start to the collaboration.

It opened at the Gielgud Theatre in September 2018 and the cast included Rosalie Craig as Bobbie, Patti LuPone as Joanne, Mel Giedroyc as Sarah and Jonathan Bailey as Jamie (originally a woman named Amy).

Elliott & Harper have also produced a new adaptation of C. S. Lewis's The Lion, the Witch and the Wardrobe with Catherine Schreiber and West Yorkshire Playhouse.

Directed by Sally Cookson, it ran at the West Yorkshire Playhouse until 27 January 2018 and transferred to the Bridge Theatre in London for Christmas 2019.

In 2019, Elliott co-directed Death of a Salesman alongside Miranda Cromwell, which starred Wendell Pierce and Sharon D. Clarke at the Young Vic Theatre with an all-black Loman family.

[14] In 2022, the company produced the West End revival of Cock by Mike Bartlett starring Jonathan Bailey at the Ambassadors Theatre for a strictly limited run.