Before achieving reality stardom, Rudy Boesch served in the U.S. Navy for 45 years

Rudy Boesch, one of the first contestants to ever appear on Survivor, has died after a long battle with Alzheimer’s disease, PEOPLE confirms. He was 91.

Boesch, a former Navy Seal, was cast on the inaugural season of the long-running reality show in 2000. Then 72, Boesch finished the season in third place and quickly became a fan favorite due to his lovably cantankerous persona.

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“Ours was an interesting bond, Dear Rudy! You and I helped open minds and undermine predjudces [sic]. While your time here has passed, you will remain loved and iconic, dear friend!” Boesch’s closest Survivor ally Richard Hatch tweeted.

More than 51 million people watched the final episode, in which Boesch was eliminated after losing the final immunity challenge. He proved so popular that he was brought back for the show’s eighth season, Survivor: All Stars. He was the second contestant voted out of that season.

Image zoom The cast of Survivor: Borneo in 2000 CBS Photo Archive/Getty

Boesch had a full life before entering the world of reality TV.

He enlisted in the United States Navy at the end of World War II in 1945. He was chosen as one of the first Navy SEALS in 1962. He completed two combat deployments during the Vietnam War, earning the Bronze Star for heroic action. He retired from the Navy in 1990 after 45 years of continuous service.

Boesch married Marjorie Thomas in 1955, and they had three children. They remained married for 53 years, until her death in 2008.

In 2000, Boesch was one of the first contestants cast on Survivor. Although he was initially in danger of being voted off the island, he joined the show’s first alliance and lasted 38 days on the beaches of Borneo.

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During season 1, Boesch’s closest ally was Hatch, the openly gay corporate trainer who ultimately won the show.

“Rudy Boesch and I both served our country in the military: he in the Navy, and I in the Army,” Hatch told PEOPLE. “But Rudy also served our country as an example of honesty and open-mindedness by respectfully engaging and aligning with me, an openly homosexual man, to play Survivor on the world stage.”

“I grew to love that cantankerous man and his family,” Hatch continued. “We are better people for having known him, and he will be sorely missed. I wish his family peace in their grieving his loss.”

Survivor: All Stars contestant Rob Cesternino also recalled his friendship with Boesch.

“Rudy was my roommate for weeks on our trip to Argentina after we both were voted out during Survivor: All-Stars,” Cesternino told PEOPLE. “I would hang on his every word because he was would tell and re-tell all these amazing stories with his unique combination of brutal honesty and a razor-sharp wit. I’ve never met anybody who could ever make me laugh as much as Rudy.”

Image zoom Survivor: All Stars cast, 2004 CBS

Survivor: Australia winner Tina Wesson was on a tribe with Boesch on Survivor: All Stars — and was amazed at the then-75-year-old’s stamina.

“What you saw on TV is exactly the man he was,” Wesson told PEOPLE. “He was tough as nails suffering from a bad case of gout on Survivor All-Stars but never really complaining about it, though his foot looked like it may fall off!”

“Rudy passionately loved two things: his wife and the military,” Wesson continued. “It was just that simple. He has always had the respect of every young whippersnapper who came out to play Survivor. Because none of us could do what he did at his age!”

In 2010, Jenn Lyon, who placed fourth on Survivor: Palau, died after a six-year battle with breast cancer. Original Survivor contestant BB Andersen died of brain cancer in 2013 at age 77. In 2014, 26-year-old Blood vs. Water contestant Caleb Bankston was killed in a railway accident. Survivor Gabon contestant Dan Kay died in 2017, and Survivor: China’s Ashley Massaro died of suicide earlier this year.