English writer of essays, short stories, screenplays, and novels. Her fiction is noted for its sensitive, sometimes wry look at the challenges and complexities of modern life in England and the United States.

Gilliatt briefly attended Queen's College, London, and Bennington (Vermont) College. After winning a fiction-writing award from British Vogue, Gilliatt joined the magazine's staff and became its features editor. She later worked as a film critic for The Observer and The New Yorker. (New Yorker, The) Her essays are collected in Unholy Fools (1973), Three-Quarter Face (1980), and To Wit: Skin and Bones of Comedy (1990).

Gilliatt wrote the screenplay Sunday, Bloody Sunday (1971; filmed 1971), about a middle-aged man and woman and the young male lover they share. The ménage-à-trois theme appears throughout her novels—One by One (1965), A State of Change (1967), The Cutting Edge (1978), Mortal Matters (1983), and A Woman of Singular Occupation (1988). Her short stories are collected in the volumes What's It Like Out? (1968), Nobody's Business (1972), Splendid Lives (1977), Quotations from Other Lives (1982), They Sleep Without Dreaming (1985), 22 Stories (1986), and Lingo (1990).