Slater was born Helen Rachel Slater in Massapequa, New York, the daughter of Alice Joan (née Citrin), a lawyer and nuclear disarmament peace activist based in New York, and Gerald Slater, a television executive; the two divorced in 1974. She has a brother, David, who is a lawyer in New York City. Her family is Jewish. Slater attended the High School of Performing Arts, graduating in 1982. In Read more...

She made her acting debut in the ABC Afterschool Special Amy and the Angel, transmitted in 1982, alongside James Earl Jones, Meg Ryan, and Matthew Modine. This was also the only film she appeared in as a brunette. In 1984, she was cast as the title character, versus Faye Dunaway as Selena, in the film Supergirl, released in 1984. The film, directed by Jeannot Szwarc, received mixed reviews, and Read more...

Slater co-founded the New York theater group, The Naked Angels, with Gina Gershon. Her stage credits include appearances in Grease, and Shakespeare and Friends. Off-Broadway, she starred in Responsible Parties and Almost Romance. She also attended classes at both NYU and UCLA, to broaden her acting abilities.