This statuesque, auburn-haired New Jersey native began her career as a print model in San Francisco. After appearing in small roles in "Bullitt" (1968) and "Fools" (1970), she relocated to L.A. to pursue an acting career. She went on to play supporting roles in a number of memorable features in the 1970s and early 80s, including Bob Rafelson's "Stay Hungry" (1976), Robert Benton's "The Late Show" (1977) and Ridley Scott's "Blade Runner" (1982). Cassidy gave a superb performance as a tough journalist covering revolutionary Nicaragua in Roger Spottiswoode's overlooked gem "Under Fire" (1982). After a sojourn in TV, she returned to screen roles and won praise as Bob Hoskins' romantic partner in Robert Zemeckis' "Who Framed Roger Rabbit" (1988). She later offered an amusing turn as Christina Applegate's business mentor in "Don't Tell Mom the Babysitter's Dead" (1991) and had supporting roles in "Vampire in Brooklyn" (1995), "Chain Reaction" (1996), "Dangerous Beauty" (1998) and "Ghosts of Mars" (2001), among scores of other roles.
On the small screen, Cassidy has enlivened many series, although in most, she far outshone the material. She was a regular on the CBS variety series "Shields and Yarnell" (1977) and went on to appear in such now-forgotten fodder as "The Rollergirls" (NBC, 1978), "240 Robert" (ABC, 1979-80) and "Codename: Foxfire" (NBC, 1985). Cassidy shone as the TV director with an on-again, off-again relationship with her arrogant star (Dabney Coleman) in the superior sitcom "Buffalo Bill" (NBC, 1983-84), a role that earned her a Golden Globe Award and an Emmy nomination. The gifted actress has also graced many TV-movies and miniseries, including "Hollywood Wives" (ABC, 1985); "Live! From Death Row" (Fox, 1992); "Barbarians at the Gate" (HBO, 1993), opposite James Garner in the tale of real-life corporate raiders; "Other Mothers", a 1993 "CBS Schoolbreak Special", in which she was the lesbian mother of a teenager; and a delicious turn as Caroline Kass opposite Cybill Shephard in "Martha, Inc.: The Story of Martha Stewart" (CBS, 2003)--dozens more telepics and miniseries would accumlate on her always-expanding resume.
Cassidy would continue try her hand at regular series television from time to time--including the short-lived projects Dudley Moore sitcom "Dudley" and the nightime soap "Hotel Malibu" (1994)--but she was far more successful in a variety of recurring roles on established hits, including "Falcon Crest," "L.A. Law," "Melrose Place," "Diagnosis Murder," "The District" and "Enterprise." The best of these semi-regular stints was her acerbic, amoral, unedited character Margaret Chenoweth, the self-obsessed psychologist mother of Brenda (Rachel Griffiths) and Billy (Jeremy Sisto), a no-punches-pulled role that Cassidy attacked with obvious glee.