Jack S. Margolis is an American counterculture writer, screenwriter, and actor. He is known for his pro-marijuana book A Child's Garden Of Grass, which he developed into a comedy album in 1971 with Jere Alan Brian and producer Ron Jacobs (2).

Margolis also worked as a screenwriter and wrote the script for Claudio Guzmán's 1975 film Linda Lovelace for President. Prior to that, Margolis wrote the Jay Ward Productions film, The Nut House!! (1964). His most notable acting appearance was as Big Bear in the Peter Sellers film "I Love You, Alice B. Toklas!" He also appeared in small parts in a few low-budget films in the 1990's.