Warren Frost, who played Will “Doc” Hayward on the original and upcoming versions of Twin Peaks and George Costanza’s cabin-cherishing almost-father-in-law on Seinfeld during a half-century acting career, died today in Middlebury, VT, after a long illness. He was 91. The news was reported by his son, Twin Peaks co-creator Mark Frost.

“From the Normandy shores on D-Day to his 50-year career on stage and screen, he remained the same humble guy from Vermont who taught us that a life devoted to telling the right kind of truths can make a real difference in the lives of others,” his family said in a statement. “We’re grateful to have shared him with the world for as long as we did.”

Born on June 5, 1925, in Newburyport, MA, Frost joined the Navy at 17 and was offshore at Normandie shelling the Germans during D-Day and for more than two weeks afterward. Following the war, he married and moved to New York City, where he landed a job in the drapery department at CBS. He would go on to spend three years as the floor director and stage manager for Philco Playhouse, one of the foundational weekly live dramas of television’s Golden Age. Working closely with greats like Sidney Lumet, John Frankenheimer and George Roy Hill led eventually to Frost’s parallel career as a theater director.

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He moved to Los Angeles in 1958 to continue working in TV, guesting on episodes of such popular series as Perry Mason and Dragnet and appearing in features including The Mating Game, It Started with a Kiss and Slaughterhouse-Five.

Frost moved to Minnesota in 1967 and became a fixture in the Twin Cities’ theater scene for the next 20 years. He relocated back to NYC in 1988 and resumed his TV acting career. He appeared on such popular dramas as Quantum Leap and L.A. Law before landing his signature role as the physician/coroner in Twin Peaks who refused to perform an autopsy on Laura Palmer. Frost appeared in all 30 episodes of the original series co-created by his son and David Lynch, and reprises the role in Showtime’s revival, which premieres May 21.

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Frost continued to work in series television throughout the 1990s, guesting on series including Get a Life, Grace Under Fire and playing Garry Shandling’s dad in a 1994 episode of The Larry Sanders Show. He also recured as Billy Lewis on Matlock for a few seasons. Perhaps his most memorable role of that era was recurring on the decade’s biggest sitcom. He played Mr. Ross, the father of George’s ill-fated fiancee Susan, in a half-dozen episodes of Seinfeld from 1992-98. His first appearance was a scene-stealer, when it was disclosed during a family dinner that his character had had a secret relationship with novelist John Cheevers.

Frost retired in 2000 and moved back to Vermont but returned to acting to appear in the upcoming Twin Peaks.

Along with son Mark, he is survived by his wife of 68 years, Virginia; son Scott Frost; daughter Lindsay Frost, an actress; and grandsons, Lucas Giolito, Casey Giolito and Travis Frost.