Ruth Seid was an American author of novels, short stories and television scripts.
Seid was born on July 1, 1913, in Brooklyn, New York. She spent most of her youth in Cleveland, Ohio in a family of Russian Jewish immigrants who struggled to escape poverty. She was the valedictorian of her high school class.
After graduation, Seid became a professional writer. She wrote short stories and radio and television scripts to help support her family. When writing novels, she used the penname Jo Sinclair, and her works usually focused on class, racial, and homosexual issues. Her first novel, Wasteland, won the Harper & Brothers Prize for new writers in 1946. She wrote three additional novels, as well as her autobiography. Seid died on July 4, 1995.