James Arness, a great Sequoia tree in the forest of TV Western heroes, has died; he was 88. Arness is immortal in TV history as Marshal Matt Dillon on Gunsmoke, the longest-running network drama in television history with the most episodes. (Gunsmoke‘s 635 episodes versus Law & Order’s 456; the two are tied with 20 seasons.) This feat would have been impossible without the presence of Arness, a 6-foot-7, quiet man who gave an air of serene authority to Matt Dillon.

Seen now on cable reruns, Gunsmoke looks like an old-fashioned Western, filled with shoot-outs (Marshal Dillon was reluctant to draw his gun, but when he did, the villains went down in the Dodge City dust), swinging-door saloons (Miss Kitty, played by Amanda Blake, ran the Long Branch Saloon and had a special, if discreet, relationship with Matt), and colorful supporting characters, most notably Dennis Weaver, as the limping, earnest Chester; Milburn Stone as the wise Doc Adams; Ken Curtis as the cornpone comic-relief Festus; and, in later seasons, Burt Reynolds as the town blacksmith, Quint Asper.

But in its time — 1955–75 — Gunsmoke was considered something new, a more serious, thoughtful, “adult” Western, as opposed to the kid-friendly, rootin’-tootin’ shoot-’em-ups of early TV such as The Roy Rogers Show and The Lone Ranger. Arness, who had little formal training as an actor, radiated a firm confidence. Originally a radio series, Gunsmoke was conceived in its transition to television as an ideal vehicle for someone such as John Wayne. Depending on which interview you read, Wayne either declined to star or wasn’t offered the role, but he did introduce the first episode, urging viewers to watch Arness, with whom Wayne had worked in movies such as Big Jim McLain and Hondo: “He’s a young fellow, and maybe new to some of you,” said Wayne. “But I’ve worked with him and I predict he’ll be a big star.”

Wayne’s thumbs-up helped Gunsmoke initially, but it took a few seasons for the show to become a huge success. The key to this was Arness’ portrayal of Matt Dillon as a ruminative man with a strong code of honor that gained him the love and loyalty of millions of viewers. Arness’ Dillon was a modern Western hero, unflinching when it came to meting out justice — murderers who didn’t surrender got shot by the Marshal, who tried to avoid violence but knew it was sometimes necessary.

Falling somewhere between the escapism of The Lone Ranger and the bloody realism of Sam Peckinpah’s revisionist films such as The Wild Bunch, Gunsmoke was a crucial link in the development of the Western. Gunsmoke owed something to features such as High Noon and the Westerns directed by John Ford and Howard Hawks, but Arness helped turn the show into something unique for the small screen. The series possessed an eclectic, elastic quality. One week, you could have a comic-relief episode with the Marshal joshing around with Chester and Festus; the next, the tone could turn grim, even doom-struck, the Western equivalent of a hard-boiled novel. This is one measure of both the show’s greatness, and Arness’ fully inhabited performance as Dillon.

Thanks to Arness and his fellow cast members, Gunsmoke might be considered one of the first workplace-family shows on TV. Matt, Kitty, Chester, and Doc would spend a lot of time just sitting around and talking — the dialogue was good enough to sustain the action. (Amanda Blake once said wryly, “This is the only show on TV where the characters sit in a barroom and say hello for half an hour.”)

But the plots often found Arness at the center of an injustice that needed to be set right. A progressive show, it featured plots that had Marshal Dillon protecting black and Indian characters from mob violence. Dillon stood up for indigent farmers and helpless women of ill repute.

The show took full advantage of Arness’ imposing demeanor. From the opening credits to many climactic showdowns, the camera framed Arness in the center, a big, silent man, awaiting either peace or violence, commanding attention amidst even the most boastful or colorful of bad guys.

Arness was a veteran of World War II, and a recipient of the Bronze Star and the Purple Heart. He acted in numerous films, including Them! Arness’ younger brother was the actor Peter Graves; it’s striking that these siblings starred in shows that helped define their genres, the Western, and in Graves’ case, the spy story (Mission: Impossible).

On his website, Arness wrote a letter to his fans “to post on our website in the event I was no longer here.” He expressed gratitude for his long career, love for his wife, Janet, and wrote to his fans in conclusion: “Thank you again for the many letters, cards, and emails we received from you over the years. You are and always have been appreciated. Sincerely, Jim Arness.”

Twitter: @kentucker