Malcolm Marmorstein was an American screenwriter.

With a career that began as a stagehand on Broadway, Marmorstein moved into television where he was a stage manager on programs such as Johnny Carson's Who Do You Trust? and Dick Clark's American Bandstand.

He is perhaps best known for his work on the soap opera Dark Shadows, penning 82 episodes, and for writing both versions of the film Pete's Dragon (1977 and 2016).

Marmorstein began writing for television in the 1960s, including episodes of The Doctors, Directions, Night Gallery, and Peyton Place, and went on to write a number of screenplays including three films with Elliot Gould: S*P*Y*S (1974), Whiffs (1975), and Dead Men Don't Die (1990), as well as Return from Witch Mountain (1978) and Love Bites (1993).

Marmorsein died November 21, 2020, in Los Angeles, California. He was 92.