Mariclare Catherine Costello (February 3, 1936 – April 17, 2026) was an American actress. She was a lifetime member of The Actors Studio. Costello's most notable role was that of 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.

Filmography

• 2000Shadow of the Blair Witch — Kathy Patterson
• Chicago Hope — Mother Mary Catherine
• 1993Indecent Proposal — David's Mother
• 1990Appearances — Rose
• 1990She Said No — Susan Finn
• 1987American Harvest — Mary Alice Duncan
• 1985Heart of a Champion: The Ray Mancini Story — Ellen Mancini
• Murder, She Wrote — Cassie Latham Burns
• 1984The Adventures of Buckaroo Banzai Across the 8th Dimension — Senator Cunningham
• 1984Victims for Victims: The Theresa Saldana Story — Jane Bladow
• 1983Nightmares — Adele Cooney (segment "The Bishop of Battle")
• 1982Skeezer — Barbara Thompson
• 1981Coward of the County — Emma Spencer
• 1980All God's Children — Winnie Naponic
• 1980Ordinary People — Audrey
• 1980The Boy Who Drank Too Much — Louise Carpenter
• Hart to Hart — Anita Boyer
• 1977A Sensitive, Passionate Man — Pat Morris
• Lou Grant — Louise Larsen
• The Fitzpatricks — Maggie Fitzpatrick
• The Incredible Hulk — Kay Wallace
• 1976Raid on Entebbe — Gabrielle Krieger
• 1976Territorial Men — Julia Baker
• 1975Conspiracy of Terror — Mrs. Warnall
• 1974After the Fall — Louise
• 1974The Execution of Private Slovik — Antoinette Slovik
• 1974The Gun — Beryl Strauss
• Kojak — Diane Gordon
• The Waltons — Mrs. Rosemary Fordwick, Miss Rosemary Hunter, Mrs. Rosemary Fordwick (archive footage)
• 1971Let's Scare Jessica to Death — Emily
• 1970Pound — Honky Killer's Wife

Appearances as themselves (1)

• 1972Going Where I've Never Been: The Photography of Diane Arbus — Herself - Narrator