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.