James Arness, the 6-foot-6 actor who towered over the television landscape for two decades as righteous Dodge City lawman Matt Dillon in “Gunsmoke,” died today. He was 88. The actor died in his sleep at his home in Brentwood, Calif., according to his business manager, Ginny Fazer. Arness’ official website posted a letter from Arness on Friday that he wrote with the intention that it be posted posthumously: “I had a wonderful life and was blessed with … (so) many loving people and great friends,” he 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.” As U.S. Marshal Dillon in the 1955-75 CBS Western series, Arness created an indelible portrait of a quiet, heroic man with an unbending dedication to justice and the town he protected. The wealth and fame Arness gained from “Gunsmoke” could not protect him from tragedy in his personal life: His daughter and his former wife, Virginia, both died of drug overdoses. Arness, a quiet, intensely private man who preferred the outdoor life to Hollywood’s party scene, rarely gave interviews and refused to discuss the tragedies. “He’s big, impressive and virile,” co-star Amanda Blake (Miss Kitty) once said of Arness, adding, “I’ve worked with him for 16 years, but I don’t really know him.” The actor was 32 when friend John Wayne declined the lead role in “Gunsmoke” and recommended Arness instead. Afraid of being typecast, Arness initially rejected it. “Go ahead and take it, Jim,” Wayne urged him. “You’re too big for pictures. Guys like Gregory Peck and I don’t want a big lug like you towering over us. Make your mark in television.” “Gunsmoke” went on to become the longest-running dramatic series in network history until NBC’s “Law & Order” tied in 2010. Arness’ 20-year prime-time run as the marshal was tied only in recent times, by Kelsey Grammer’s 20 years as Frasier Crane from 1984 to 2004 on “Cheers” and then on “Frasier.” The years showed on the weathered-looking Arness, but he — and his TV character — wore them well. “The camera really loved his face, and with good reason,” novelist Wallace Markfield wrote in a 1975 “Gunsmoke” appreciation in The New York Times. “It was a face that would age well and that, while aging, would carry intimations of waste, loss and futility.” Born James Aurness in Minneapolis (he dropped the “u” for show business reasons), he and brother Peter enjoyed a “real Huckleberry Finn existence,” Arness once recalled. Peter, who changed his last name to Graves, went on to star in the TV series “Mission Impossible.” A self-described drifter, Arness left home at age 18, hopping freight trains and Caribbean-bound freighters. He entered Beloit College in Wisconsin, but was drafted into the Army in his 1942-43 freshman year. Wounded in the leg during the 1944 invasion at Anzio, Italy, Arness was hospitalized for a year and left with a slight limp. He returned to Minneapolis to work as a radio announcer and in small theater roles. He moved to Hollywood in 1946 at a friend’s suggestion. After a slow start in which he took jobs as a carpenter and salesman, a role in MGM’s “Battleground” (1949) was a career turning point. Parts in more than 20 films followed, including “The Thing,” ‘’Hellgate” and “Hondo” with Wayne. Then came “Gunsmoke,” which proved a durable hit and a multimillion-dollar boon for Arness, who owned part of the series. His longtime co-stars were Blake as saloon keeper Miss Kitty, Milburn Stone as Doc Adams and Dennis Weaver as the deputy, Chester Goode. When Weaver died in February 2006, Arness called it “a big loss for me personally” and said Weaver “provided comic relief but was also a real person doing things that were very important to the show.” The cancellation of “Gunsmoke” didn’t keep Arness away from TV for long: He returned a few months later, in January 1976, in the TV movie “The Macahans,” which led to the 1978-79 ABC series “How the West Was Won.” Arness took on a contemporary role as a police officer in the series “McClain’s Law,” which aired on NBC from 1981-82. Despite his desire for privacy, a rocky domestic life landed him in the news more than once. Arness met future wife Virginia Chapman while both were studying at Southern California’s Pasadena Playhouse. They wed in 1948 and had two children, Jenny and Rolf. Chapman’s son from her first marriage, Craig, was adopted by Arness. The marriage foundered and in 1963 Arness sought a divorce and custody of the three children, which he was granted. He tried to guard them from the spotlight. “The kids don’t really have any part of my television life,” he once remarked. “Fortunately, there aren’t many times when show business intrudes on our family existence.” The emotionally troubled Virginia Arness attempted suicide twice, in 1959 and in 1960. In 1975, Jenny Arness died of an apparently deliberate drug overdose. Two years later, an overdose that police deemed accidental killed her mother. Arness married Janet Surtees in 1978. Besides his wife, Arness is survived by two sons and six grandchildren. A private memorial service will be held.