Hassett is best known for her portrayal of skier Jill Kinmont is the film The Other Side of the Mountain (1975), which was directed by Larry Peerce, who chose her for the lead from several hundred hopefuls. Consequently, she won a Golden Globe in 1976 for New Star of the Year. The film ended up being Universal Studios' highest-grossing film for 20 years. Marilyn also co-starred with Jan-Michael Vincent in the 1976 cult classic Shadow of the Hawk.
She later married Peerce and appeared in several films he directed, including Two-Minute Warning (1976), The Other Side of the Mountain Part 2 (1978) and the 1979 film adaptation of Sylvia Plath's The Bell Jar. Peerce and Hassett subsequently divorced and she never remarried.
