Forrest passed away in Providence, Rhode Island on 25 July (10) after a year-long battle with a brain tumour.
She began a successful casting career in the 1980s, and made her mark on U.S. television series Crash and feature length films including Light and the Sufferer, for which she was also executive producer.
As an actress, she co-starred in George Lucas' 1971 sci-fi film THX1138 and made appearances in hit series L.A. Law.
She also appeared in films including Communion, Baby Fever and Sitting Ducks, for which she earned a National Association of Film Critics Award nomination for best supporting actress.
She later taught acting in Los Angeles and Portland, Oregon.
Forrest is survived by her brother, Andrew Cagen, two nieces and a nephew.