BOISE, Idaho — George Kennedy, the veteran actor who built his early career playing heavies and won an Academy Award in 1968 for his supporting role as the tough Southern prison-camp convict who grew to hero-worship Paul Newman’s defiant title character in “Cool Hand Luke,” died Sunday in Boise, Idaho, of natural causes, said his grandson Cory Schenkel. He was 91.

In a more than 50-year screen career, the deep-voiced Kennedy appeared in dozens of movies, including “The Flight of the Phoenix,” “The Sons of Katie Elder,” “The Dirty Dozen,” “Earthquake,” “Cahill United States Marshal,” “The Eiger Sanction,” “Death on the Nile,” and the “Airport” series of films.

In a distinct change of pace in the late ’80s and ’90s, he played Capt. Ed Hocken in the “Naked Gun” series of cop spoofs starring Leslie Nielsen as Detective Lt. Frank Drebin.

“I had the time of my life doing it,” Kennedy told New York’s Newsday after making the first one in 1988. “It’s so funny, it was hard to shoot the movie.”

A World War II combat veteran, Kennedy spent 16 years in the Army before launching his career in Hollywood in the late 1950s. At 6-foot-4 and 230 pounds, he was initially typecast as the bad guy in TV westerns and in films.

He went after Joan Crawford with an ax in “Strait-Jacket,” savagely attacked Audrey Hepburn with a prosthetic hand hook in “Charade” and attempted to assassinate Gregory Peck in “Mirage.”

Then came his breakout role in “Cool Hand Luke,” the hit 1967 film starring Newman as the newcomer to the road gang at a prison work-camp.

“I was completely overwhelmed when I saw the script,” Kennedy recalled in a 2003 interview with the Tennessean newspaper. “I remember saying to my agent, ‘They’re not going to give me this role. I’m one of those third-guy-through-the-door bad guys.’”

But, he said, “I screen-tested and lucked out. The test was very, very good; no way I was not going to take it seriously.”

As Dragline, Kennedy becomes Luke’s friend and biggest booster after the smaller Luke stubbornly refuses to stay down when Dragline brutally pummels him in a prison yard boxing match.

For the movie’s famous scene in which Newman’s Luke eats 50 hardboiled eggs in an hour on a bet, Kennedy’s character serves as Luke’s trainer and “official egg peeler.”

In his review of the film, the Los Angeles Times’ Charles Champlin noted that “it will almost certainly do for George Kennedy what ‘Cat Ballou’ did for Lee Marvin — pay off with stardom in a long honorable hitch at lesser servitude.”

It was a beaming Kennedy who took the stage to accept the Oscar for his career-changing performance.

“Oh, I could bust,” he said at the start of his brief acceptance speech.

“Winning that was the highlight single moment of my life,” he said in the 2003 interview with the Tennessean.

The Oscar represented more than just the gold-plated centerpiece for his living-room mantle.

The day he was nominated for the award, he recalled, “my salary went up 10 times.”

For a while after “Cool Hand Luke,” Kennedy told Canada’s the Globe and Mail in 1978, “I did nothing but good guys. Now I play about 75 percent good guys and 25 percent bad guys.”

In addition to doing movies in the 1970s, Kennedy starred in two TV series: as a cop-turned-priest in “Sarge,” a 1971-72 drama; and as an old-school beat cop in “The Blue Knight,” a 1975-76 police drama.

Kennedy, who played President Warren G. Harding on the 1979 miniseries “Backstairs at the White House,” also played cattle rancher Carter McKay on “Dallas” from 1988 to 1991.

He was born in New York state on Feb. 18, 1925. His mother was a member of a classical ballet dance team on the vaudeville circuit and his father was a pianist, composer and pit orchestra leader who died when Kennedy was 4.

Kennedy describes his poverty-stricken early years after his father died, including a period in which he and his mother lived in a brothel, in his 2011 book “Trust Me: A Memoir.”

During World War II, he enlisted in the Army in 1943 at 17 and served in the infantry in Europe, where he fought in the Battle of the Bulge.

Re-enlisting after the war ended, he earned a commission as an officer and became part of the Armed Forces Radio Network in Frankfurt and Berlin and later in Tokyo and Korea.

His final assignment was as the military adviser for “The Phil Silvers Show,” a popular peacetime Army sitcom shot in New York and starring Silvers as the constantly scheming Sgt. Ernie Bilko.

“I was praying one of the (regular) guys wouldn’t show up, so I could stand in for him,” Kennedy recalled in a 1968 Times interview.

It happened, said Schenkel, his grandson, when a spot opened up and someone on the set turned to him, saying, “Hey, you are a really big guy, and you look like you could play a bad guy.”

He wound up doing several bit parts as an MP on the series, which he later described as a “great training ground for me.”

Kennedy, who had been born with a curved spine, was hospitalized a number of times for spine problems before being retired from the Army with partial disability. With no job prospects, he headed to Hollywood.

Within a week of meeting with a talent agent in 1959, he was cast as a bad guy on a TV western.

“If it had been the time of shorter heroes — Eddie Robinson, Alan Ladd, Bogart — I couldn’t have gotten arrested,” Kennedy said in a 1969 interview with the Times. “But it was the era of big guys. Men Like Jim Arness and Clint Walker needed someone big to beat up in their television series.”

Kennedy’s grandson, who lived with him and helped take care of him, described the actor as “just a quiet family man” who “always put his family first and was always happy to take time out to talk to fans. He never turned a fan away, just enjoyed making movies and bringing joy to other people.”

He was preceded in death by his wife Joan Kennedy and a son and a daughter. Besides Schenkel, he is survived by daughter Shannon Sullivan and granddaughter Taylor Kennedy.