James Arness, who famously played Marshal Matt Dillon on the TV Western Gunsmoke for 20 years, passed away this morning in his Brentwood, Calif., home, the Los Angeles Times reports. He was 88.

Born in Minneapolis on May 26, 1923, the 6-foot-7 Arness began his began his career as a radio announcer in Minnesota following his discharge from the Army. He made his film debut in 1947 in The Farmer's Daughter before going on to appear in such Westerns as Wagon Master and Hondo -- he shared the big screen four times with John Wayne -- and science fiction movies like The Thing and Them!

But it was for Gunsmoke, a role that Arness took only at the urging of Wayne, that he would become best known. Wayne even introduced the first episode of the series, telling viewers in 1955 that his friend Arness was "a young fellow, and maybe new to some of you, but I've worked with him and I predict he'll be a big star." He was right. Arness would play the incorruptible Dodge City lawman Matt Dillon for 20 seasons -- 635 episodes -- until Gunsmoke's cancellation in 1975. He later reprised the role in five made-for-TV movies, portraying the marshal in five separate decades.

Following the end of Gunsmoke, Arness starred in the Western miniseries and subsequent series How the West Was Won as well as the short-lived crime drama McClain's Law and the made-for-TV movie The Alamo: 13 Days to Glory.

In a letter left for his wife Janet to post on his website "in the event I was no longer here," Arness told his fans, "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. [...] 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."

His death comes a little more than a year after that of his brother, Mission: Impossible star Peter Graves, who passed away at age 83. Arness is survived by his wife, two sons and six grandchildren.