(CNN) -- Former "Gunsmoke" actor James Arness, who played Marshal Matt Dillon in the western TV series for 20 years, died Friday from natural causes, according to his website. He was 88.

Over the two decades of "Gunsmoke" episodes from 1955 to 1975, Arness worked with hundreds of actors, some of them just up-and-comers such as Harrison Ford, Burt Reynolds and Charles Bronson. He also worked with Bette Davis.

Arness left behind a letter to his fans, which was posted on his website after his death:

"I had a wonderful life and was blessed with some many loving people and great friends. The best part of my life was my family, especially my wife, Janet. Many of you met her at Dodge City so you understand what a special person she is," Arness wrote.

"I wanted to take this time to thank all of you for the many years of being a fan of 'Gunsmoke,' 'The Thing,' 'How the West Was Won' and all the other fun projects I was lucky enough to have been allowed to be a part of. I had the privilege of working with so many great actors over the years.

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"I was honored to have served in the army for my country. I was at Anzio during WWII and it makes you realize how very precious life is," Arness wrote.

"Thank you again for all the many letters, cards, emails and gifts we received from you over the years. You are and always have been truly appreciated," he concluded.

Born in Minneapolis, Minnesota, on May 26, 1923, Arness later served in the Army and was sent in 1944 to Anzio, the Italian beach that the Army said was the setting for the largest and most violent armed conflict in the history of mankind.

Arness was wounded in his right leg and received the Purple Heart.

According to an Army website, during the four months of the Anzio Campaign, the Allied VI Corps experienced more than over 29,200 combat casualties (4,400 killed, 18,000 wounded, and 6,800 prisoners or missing) and 37,000 noncombat casualties. German combat losses were estimated at 27,500 (5,500 killed, 17,500 wounded, and 4,500 prisoners or missing), according to the Army.

Arness' acting debut was in a movie called "The Farmer's Daughter" opposite Loretta Young.

He worked for John Wayne's film production company Batjac and made movies with Wayne including "Islands in the Sky," "Hondo," "The Sea Chase" and "Big Jim McLain."

Arness also acted in the 1951 sci-fi classic "The Thing," and his 6-foot-7 height made the creature more believable, according to his website.

After "Gunsmoke," Arness continued acting in television in the mini-series "How the West Was Won" in 1978-79 and "McLain's Law" in 1981-82.

In addition to his wife, Arness is survived by two sons and six grandchildren. The services will be private.