James Arness, 88, the 6-foot-6 actor who towered over the television landscape for two decades as righteous Dodge City lawman Matt Dillon in

Gunsmoke

, died Friday.

The actor died in his sleep at his home in Brentwood, Calif., according to his business manager, Ginny Fazer.

As U.S. Marshal Dillon in the 1955-75 CBS western series, Mr. 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 Mr. 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.

Mr. 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.

The actor was 32 when friend John Wayne declined the lead role in Gunsmoke and recommended Mr. Arness. Afraid of being typecast, Mr. Arness initially rejected it.

Gunsmoke went on to become the longest-running dramatic series in network history until NBC's Law & Order tied it in 2010. Mr. 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 Mr. Arness, but he - and his TV character - wore them well.

Born James Aurness in Minneapolis (he dropped the u for show-business reasons), he and brother Peter enjoyed a "real Huckleberry Finn existence," Mr. 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, Mr. Arness left home at 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, Mr. 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 Mr. Arness, who owned part of the series.

His longtime costars were Amanda Blake as saloon keeper Miss Kitty, Milburn Stone as Doc Adams, and Dennis Weaver as the deputy, Chester Goode.

The cancellation of Gunsmoke didn't keep Mr. 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.

Mr. Arness took on a contemporary role as a police officer in the series McClain's Law, which aired on NBC from 1981-82.

Mr. 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. Mr. Arness adopted Chapman's son from her first marriage, Craig.

The marriage foundered and in 1963 Mr. Arness sought a divorce and custody of the three children, which he was granted. He tried to guard them from the spotlight.

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.

Mr. Arness married Janet Surtees in 1978. Besides his wife, Mr. Arness is survived by two sons and six grandchildren. A private memorial service will be held.