Wilford Brimley, a Utah blacksmith and horse trainer who made a career transition to movies and commercials, often stealing scenes as gruff and homespun characters in films such as “Tender Mercies,” “The Natural” and “Cocoon,” died Aug. 1 at a hospital in St. George, Utah. He was 85.

He had been on dialysis and had several medical ailments, said his manager, Lynda Bensky.

After dropping out of high school to join the Marine Corps, Mr. Brimley was a bodyguard for reclusive billionaire Howard Hughes and a wrangler for ranches throughout the West. By the mid-1960s, he was working as a farrier shoeing horses for TV westerns, and he eventually was recruited for stunts.

“I became friends with a fella named Bob Duvall,” he told the Los Angeles Times, referring to the then up-and-coming character actor, whom he met on the set of “Cimarron Strip” in 1967 and who would go on to play celebrated roles in “The Godfather” and “Apocalypse Now.” “I met him on one of them horse opera TV deals. I was fascinated with what he was able to do as an actor. I’d never see anything like it.”

Not long after, Mr. Brimley shifted from stunts to acting on the advice of a colleague who told him that “it pays better and you don’t have to hit the ground.”

With his burly physique, countrified drawl and overflowing mustache, Mr. Brimley looked every inch the prairie-roamer in Wild West oaters such as “True Grit” (1969) and “Lawman” (1971)and the drama “The Electric Horseman” (1979), starring Robert Redford as an over-the-hill rodeo rider.

He also had memorable supporting roles as a nuclear-plant worker in “The China Syndrome” (1979) opposite Jack Lemmon. And with his tinted wire-rimmed glasses, he excelled as plain-talking authority figures, including in “Brubaker” (1980) as a prison board member and in the journalism-legal thriller “Absence of Malice” (1981) as an assistant U.S. attorney general.

His career advanced to a new level in “Tender Mercies” (1983), in which he played a music manager forced to deliver hard truths about the business to Duvall’s washed-up alcoholic country singer. The next year, Mr. Brimley played the cynical baseball manager Pop Fisher in “The Natural” opposite Redford, in the title role, and Duvall as a corrupt sportswriter.

Mr. Brimley’s close friend Richard Farnsworth, who had a similar start in films as a stuntman, was also in “The Natural,” and their low-key chemistry made for a true-to-life scene in which each character tries to guess what song the other is whistling.

“We played name that tune for 25 years. It was not part of the script,” Mr. Brimley told the Powell (Wyo.) Tribune. “Not at all, not at all, we were just killing time.”

His biggest hit on-screen was “Cocoon” (1985), director Ron Howard’s crowd-pleaser — co-starring Maureen Stapleton, Don Ameche, Jessica Tandy and Hume Cronyn — about retirement home residents rejuvenated through alien technology. Mr. Brimley had a touching farewell sequence while fishing with his grandson. “By golly,” he told the Salt Lake Tribune, with a rare flash of raw pride, “that turned out to be the best damn scene in the picture.”

He reprised his role in the sequel “Cocoon: The Return” (1988) and appeared in action films such as “The Firm” (1993), in which he played, against type, a secretive law firm’s blackmailing security chief opposite Tom Cruise’s hotshot lawyer. He was also cast in comedies including “My Fellow Americans” (1996) with James Garner and Lemmon as former presidents.

On TV, Mr. Brimley had a recurring role on“The Waltons” in the 1970s and then starred in the NBC drama series “Our House” from 1986 to 1988 as an ornery grandfather who takes in his widowed daughter-in-law and her three children. He also appeared on “Seinfeld” in 1997 as a rustic but menacing U.S. postmaster general who strong-arms Kramer into ending his boycott of mail delivery.

With an undisguised aversion to Hollywood, Mr. Brimley preferred to live on his properties in Santa Clara, Utah, and Greybull, Wyo., leaving occasionally to make a film or, in one of his favorite sidelines, to sing — and sometimes record — Tin Pan Alley standards with a jazz combo.

Mr. Brimley also became a TV fixture through his work as a folksy pitchman for Quaker Oats cereal and Liberty Medical, a mail-order provider of diabetes-testing supplies. Mr. Brimley suffered from the disease and said he spoke publicly about his condition because too many people “have diabetes, and they deny it. They think there’s something to be ashamed about.”

His commercials invited parody, including a “Saturday Night Live” sketch featuring John Goodman as Mr. Brimley. In Goodman’s sendup, Mr. Brimley fakes having diabetes (“I look like somebody who would have it”) and squirts a lot of Reddi-wip whipped cream into his mouth. He also detests oats (“It always seems like someone else ate it first”).

“You can either accept that or let it bother you,” Mr. Brimley said, with good humor, of the ribbing. “I accept it.”

Anthony Wilford Brimley, the son of a real estate broker and a piano teacher, was born in Salt Lake City on Sept. 27, 1934, and grew up in Santa Monica, Calif. He quit school in eighth grade and, after years of itinerant ranch work, went back to school, years later, in Salt Lake City.

“I was a terrible student,” he told the Salt Lake Tribune. “I just couldn’t stand being cooped indoors. I tried to matriculate from the eighth grade to the 12th in one jump. It didn’t work, so I dropped out again.” He served in the Marine Corps during the Korean War and was based in the Aleutian Islands.

His first wife, the former Lynne Bagley, died in 2000. In 2007, he married Beverly Berry, who survives him along with three sons from his first marriage. Another son died in infancy.

After his encounter with Duvall, who remained a close friend for years, Mr. Brimley joined a Los Angeles theater group to train formally. “But the theater,” he told the Times, “turned into a big power struggle. They had committees and officials and I just said, ‘Forget it. I don’t want no more of it.’ ”

He experienced similar frustrations while making “The Waltons.” When the producer seemed to dismiss Mr. Brimley’s concerns about his character, the actor asked to be written out of the series — anticipating his plan to leave acting and go “back to the mountain.”

In a career that took many twists, Mr. Brimley returned to show business in 1977 after passing through Los Angeles while hauling horses to Denver. He decided to audition for a part in “The China Syndrome.” He joked that he did the audition mostly to get co-star Lemmon’s autograph, but he grudgingly admitted to finding, in performance, a way to satisfy his wandering spirit.

“It’s the greatest hiding place I know,” he told the Times. “I’m able to put those clothes on and use that name and those words and then tell the truth about myself.”