Mariclare Costello, whose portrayal of Miss Rosemary Hunter on “The Waltons” endeared her to television audiences during the 1970s, died April 17, 2026, in Brooklyn, her family announced. She was 90.
The warm-hearted character actress built a career spanning six decades across Broadway stages, television screens and movie theaters, from cult horror films to Oscar-winning dramas and prestige telefilms.
Walton’s Mountain And A Lasting Legacy
Television viewers knew Costello best as the gentle schoolteacher on CBS’ “The Waltons” who spotted young John-Boy Walton’s writing talent and encouraged him to pursue it. Between 1972 and 1977, she appeared across five seasons of the beloved family drama, with her character marrying Rev. Matthew Fordwick, the town preacher played by John Ritter before his “Three’s Company” fame.
Her television work extended to starring as the matriarch in the 1977 CBS drama “The Fitzpatricks,” which ran for one season. Guest appearances dotted the 1970s, ’80s and ’90s on shows including “Ironside,” “Kojak,” “Little House on the Prairie,” “Lou Grant,” “Murder, She Wrote,” “Santa Barbara,” “Chicago Hope,” “Judging Amy” and “Providence.”
Hollywood And A Cult Horror Classic
Costello’s 1967 film debut came in “The Tiger Makes Out” with Eli Wallach and Anne Jackson. But her most enduring cinematic role arrived in 1971 with the low-budget horror film “Let’s Scare Jessica to Death.” As Emily, a free-spirited hippie who moves in with Jessica, played by Zohra Lampert, and her husband before revealing herself as a vampire, Costello created one of the most haunting moments in 1970s horror when her undead character rises slowly from a misty lake. The film has achieved cult status in the decades since.
She took on the role of Martin Sheen’s wife in the 1974 telefilm “The Execution of Private Slovik.” In Robert Redford’s 1980 Oscar-winning “Ordinary People,” she played the sympathetic sister-in-law to Mary Tyler Moore’s grieving mother.
From Peoria To The Bright Lights
The youngest of three sisters in a creativity-prizing family, Costello was born Feb. 3, 1936, in Peoria, Illinois. She studied at Clarke College in Iowa, then earned a master’s degree in theater and education from Catholic University, training in improvisation under legendary instructor Viola Spolin. While in Washington, she performed as Nerissa in “The Merchant of Venice” for President John F. Kennedy.
Moving to New York City after graduate school, Costello joined the Lincoln Center Repertory Company as an original member and became a lifetime member of The Actors Studio. The stage became her first love. She made her Broadway debut in 1964 opposite Jason Robards in Arthur Miller’s “After the Fall,” launching nine productions between 1964 and 1970.
Her Broadway credits accumulated 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 revival of “Harvey” with James Stewart and Helen Hayes.
A Life Beyond The Screen
In an acting class taught by Mira Rostova, Costello met “M*A*S*H” actor Allan Arbus, her future husband. The two fell in love while rehearsing a Dorothy Parker play. They married in 1977 and stayed together until his death in 2013.
Family and friends recalled her as a teacher, mentor, wonderful cook and animal lover whose curiosity shaped every aspect of her life. “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.”
Costello 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 funeral service will be held in New York City, with burial and a remembrance to follow in her hometown of Peoria.