Instagram/Mariclare Costello & Alla Celebrity Mariclare Costello, 'The Waltons' actress and star of cult horror film 'Let's Scare Jessica to Death,' dies at 90. April 28, 2026 AceShowbiz - Mariclare Costello, known for her role as the devoted schoolteacher Rosemary Hunter on The Waltons, passed away on Friday, April 17, in Brooklyn. She was 90 years old, according to her family. Mariclare Costello also gained recognition for her portrayal of a free-spirited hippie-turned-vampire in the 1971 cult horror film Let's Scare Jessica To Death.