Jean Lyndsey Torren Marsh (born 1 July 1934) is a Golden Globe-nominated English actress and writer, who is perhaps best known for co-creating the British period drama Upstairs, Downstairs with Eileen Atkins. She also portrayed house parlourmaid Rose Buck in the same series. Marsh and Atkins also co-created the 1991 television series The House of Eliott. Marsh has had several film appearances, including playing the primary villainess in both the popular fantasy films Return to Oz (1985) and Willow (1988).

Marsh was born in Stoke Newington, London, England, the daughter of Emmeline Susannah Nightingale Poppy (née Bexley), a bar employee and dresser for the theatre, and Henry Charles John Marsh, an outdoor maintenance person and printer's assistant.

Marsh made many appearances on British and American television programmes in the 1950s and 1960s, including The Twilight Zone (in a memorable episode in which she played a prisoner's robotic companion) and UFO. In the early '70s, she hosted the short-lived International Animation Festival on PBS. She also had a role as the office spy, Roz in the failed television series based on the movie of the same name, 9 to 5 as well as an appearance in Hawaii Five-0 (The Miracle Man/ playing "Sister Harmony").

She was once married to Jon Pertwee, the third actor to play the character of Doctor on the television series Doctor Who. Marsh herself appeared three times in the series, both before and after Pertwee's era, playing different characters, including the First Doctor's companion Sara Kingdom. Her part of Morgaine in the serial Battlefield is similar to her roles in the above-mentioned fantasy films. In the 1990s, she starred in a villain role in the Nickelodeon re-make of The Tomorrow People.

In 2000, Marsh had a starring role in the CBBC drama The Ghost Hunter, as the evil Mrs Croker. The Ghost Hunter ran for three series from 2000–2002. Marsh also made an appearance in the Blue Peter Quest in 2003 as the villain, Stryker. As of October 2007, Marsh was again playing the part of a maidservant, this time playing the housekeeper Bertha on the London West End stage in a revival of Boeing Boeing at the Comedy Theatre. She also made an appearance in the 2007 BBC adaptation of Jane Austen's Sense & Sensibility, playing the Dowager Mrs Ferrars.

Marsh lives in Boxford, Berkshire.

Born in London on 1 July 1934, Jean Marsh became interested in show business while taking dancing and mime classes as therapy for a childhood illness. After attending a charm school and working as a model, she started acting in repertory and took voice lessons. Her repertory work was supplemented by a number of film appearances as a dancer. She then spent three years in America, appearing in Sir John Gielgud's Broadway production of "Much Ado About Nothing" and numerous TV shows, including an episode of "Twilight Zone, The" (1959). Returning to London, she won roles on stage, film and TV. It was during this period that she appeared in "Doctor Who" (1963), first as Princess Joanna in "The Crusade" and then as Sara Kingdom in "The Daleks' Master Plan." In the early 1970s she co-created and starred in LWT's "Upstairs, Downstairs" (1971). Since then she has maintained a very busy career in the theatre, on TV - including a starring role in the US sitcom "9 to 5" (1982) and films such as Return to Oz (1985) and Willow (1988). She also co-created another successful series, "House of Eliott, The" (1991).