Career
Costello"s most notable role was Rosemary Hunter Fordwick on the television series The Waltons, from 1972 to 1977. In 1977, after her role on The Waltons, she played matriarch Maggie Fitzpatrick on the short-lived drama show The Fitzpatricks. Costello was born in Peoria, Illinois.
Her first film appearance was in The Tiger Makes Out (1967).
In 1970, she appeared on stage in "Harvey" at the American National Theatre and Academy Theatre, in New York City. She is also well remembered for her role as a hippie-vampire in the 1971 cult horror film Let"s Scare Jessica to Death.
In the 1981 Miloš Forman film Ragtime, she portrayed Emma Goldman in a scene that was ultimately deleted from the theatrical release, but still included on the Digital Video Disc. She now works as an acting professor at Loyola Marymount University in Los Los Angeles