Simon Gray is primarily known as a stage dramatist, but he began his playwriting career as an author of television scripts, including The Caramel Crisis (1966), Death of a Teddy Bear (1967), A Way with the Ladies (1967), Sleeping Dog (1967), Pig in a Poke (1969), The Dirt on Lucy Lane (1969), Style of the Countess (1970), The Princess (1970), and Man in a Sidecar (1971).

Besides being a successful dramatist, Gray also published novels: Colmain (1963), Simple People (1965), Little Portia (1967), A Comeback for Stark (1968; under the pseudonym Hamish Reade), and Breaking Hearts (1997). Gray also used the pen name James Holliday. Gray became editor of Delta magazine in 1964, and he coedited with Keith Walker an anthology entitled Selected English Prose that was published in 1967.

In 1975, the playwright wrote the screenplay version of his play for the film Butley, directed by Harold Pinter and starring Alan Bates, re-creating his stage role as the title character. The movie was made as part of the American Film Theatre series.

Simon Gray received many of the highest awards for dramatists. Death of a Teddy Bear won a Writers Guild Award, Butley received the Evening Standard (London) Award for Best Play of the Year in 1972, and Otherwise Engaged was voted Best Play by the New York Drama Critics Circle. Moreover, the filming of Butley and the option taken to film Death of a Teddy Bear are indicators of the dramatist’s popularity.