Mariclare Costello, whose recurring role as schoolteacher Rosemary Hunter on “The Waltons” made her a beloved presence in American homes during the 1970s, has died at age 90.
Her family announced that Costello died April 17, 2026, in Brooklyn. The character actress built a career spanning six decades that included Broadway stages, cult horror films, prestige television movies and Academy Award-winning features.
From Peoria to the Bright Lights
The youngest of three sisters in a creative Peoria, Illinois, family, Costello was born Feb. 3, 1936. She studied at Clarke College in Iowa before obtaining a master’s degree in theater and education from Catholic University, where legendary instructor Viola Spolin taught her improvisation. While in Washington, she performed as Nerissa in “The Merchant of Venice” for President John F. Kennedy.
After earning her degree, Costello moved to New York City, where she became an original member of the Lincoln Center Repertory Company and earned lifetime membership in The Actors Studio. The stage became her primary passion. In 1964, she made her Broadway debut opposite Jason Robards in Arthur Miller’s “After the Fall,” launching a string of nine Broadway shows through 1970.
Her productions came rapidly: “But For Whom Charlie” (1964), “The Changeling” (1964), “Tartuffe” (1965), “Danton’s Death” (1965), “The Country Wife” (1965), “Lovers and Other Strangers” (1968), “A Patriot for Me” (1969), and a 1970 “Harvey” revival starring James Stewart and Helen Hayes.
Hollywood and a Cult Horror Classic
Costello’s first film appearance came in 1967’s “The Tiger Makes Out” with Eli Wallach and Anne Jackson. While television audiences knew her best from “The Waltons,” horror fans revere her for her chilling performance in the 1971 low-budget film “Let’s Scare Jessica to Death.” She portrayed Emily, a seemingly carefree hippie who moves in with Jessica, played by Zohra Lampert, and her husband before exposing herself as a vampire. Her slow emergence from a fog-covered lake became an iconic image in 1970s horror cinema, and the film’s cult following has only intensified over the years.
Her screen work also included a role as the wife of Martin Sheen’s character in the critically praised 1974 telefilm “The Execution of Private Slovik.” In 1980, she played the compassionate sister-in-law to Mary Tyler Moore’s devastated mother in Robert Redford’s Oscar-winning drama “Ordinary People.”
Walton’s Mountain and a Lasting Legacy
Between 1972 and 1977, Costello appeared across five seasons of CBS’ “The Waltons” as Miss Rosemary Hunter, the compassionate schoolteacher who spotted young John-Boy Walton’s talent and urged him to pursue a writing career. Her character later wed the town preacher, Rev. Matthew Fordwick, portrayed by John Ritter before his “Three’s Company” fame.
She also headlined the short-lived 1977 CBS series “The Fitzpatricks” as the family matriarch. Her television work throughout the 1970s, ’80s and ’90s included guest appearances on “Ironside,” “Kojak,” “Little House on the Prairie,” “Lou Grant,” “Murder, She Wrote,” “Santa Barbara,” “Chicago Hope,” “Judging Amy” and “Providence.”
A Life Beyond the Screen
In an acting class led by Mira Rostova, Costello encountered Allan Arbus, the “M*A*S*H” actor who would become her husband. Romance blossomed during rehearsals for a Dorothy Parker play. The couple wed in 1977 and remained together until his death in 2013.
Those close to her recalled Costello as more than an actress—she was a teacher, mentor, skilled cook and animal enthusiast whose inquisitiveness touched every aspect of her existence. “She was also, in every dimension of her life, someone who paid attention,” her family wrote. “She could talk to anyone, was interested in everything, and was a relentless asker of questions.”
She is survived by her daughter, stage director Arin Arbus, and Arin’s partner, playwright Ethan Lipton; her granddaughter, Bird; and stepdaughters Amy and Doon. A New York City funeral service is planned, followed by burial and a memorial gathering in Peoria.
