Mariclare Costello, whose portrayal of compassionate schoolteacher Rosemary Hunter on “The Waltons” made her a familiar face to television audiences across America, has died at age 90.
Her family announced that Costello passed away April 17, 2026, in Brooklyn. Her career spanned more than 60 years, encompassing Broadway theater, horror films that became cult classics, award-winning cinema and countless television appearances.
From Peoria To The Bright Lights
The youngest of three sisters, Costello was born Feb. 3, 1936, in Peoria, Illinois, into a family that valued the arts. After studying at Clarke College in Iowa, she earned a master’s degree in theater and education from Catholic University, studying improvisation with the renowned Viola Spolin. While in Washington, she performed as Nerissa in “The Merchant of Venice” for President John F. Kennedy.
Following graduate school, she relocated to New York City and joined the Lincoln Center Repertory Company as an original member while also becoming a lifetime member of The Actors Studio. Theater remained her greatest passion. In 1964, she debuted on Broadway in Arthur Miller’s “After the Fall” with Jason Robards, launching an impressive streak of nine Broadway shows from 1964 through 1970.
Between those years, 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” alongside James Stewart and Helen Hayes.
Hollywood And A Cult Horror Classic
While Costello appeared in the 1967 film “The Tiger Makes Out” with Eli Wallach and Anne Jackson, it was a modestly budgeted 1971 horror picture that cemented her place in genre film history.
In “Let’s Scare Jessica to Death,” she portrayed Emily, a bohemian drifter who joins Jessica (Zohra Lampert) and her husband before being revealed as a vampire. The enduring image of Costello’s vampiric character emerging from a fog-shrouded lake stands as one of the most chilling scenes in 1970s horror cinema, and the film’s cult following has grown stronger over time.
Her film work included playing Martin Sheen’s wife in the 1974 telefilm “The Execution of Private Slovik.” She later appeared in Robert Redford’s 1980 Oscar-winning drama “Ordinary People” as the understanding sister-in-law to Mary Tyler Moore’s character.
Walton’s Mountain And A Lasting Legacy
Television viewers will always remember Costello as Miss Rosemary Hunter, the nurturing teacher on Walton’s Mountain who recognized young John-Boy Walton’s writing talent and encouraged him to pursue his literary dreams. The role ran across five seasons from 1972 to 1977 on CBS’ “The Waltons,” during which her character wed the town preacher, Rev. Matthew Fordwick, portrayed by John Ritter before his “Three’s Company” fame.
Her television work extended far beyond Walton’s Mountain. Costello played the matriarch in CBS’ short-lived 1977 series “The Fitzpatricks,” and made guest appearances on numerous shows throughout the 1970s, ’80s and ’90s, including “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 “M*A*S*H” actor Allan Arbus, with whom she fell in love while performing in a Dorothy Parker play. The couple married in 1977 and remained together until his death in 2013.
Those who knew her recalled Costello as more than an actress — she was an educator, guide, skilled cook and devoted animal lover whose boundless curiosity 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. Funeral services are planned for New York City, followed by burial and a memorial in Peoria.
