Police said they were alerted to the death of the actor, who won fame as the wandering monk in the "Kung Fu" television series, on Thursday morning.
"He was found hanging by a rope in the room's closet," Lieutenant Colonel Pirom Jantrapirom of the Lumpini police station in Bangkok told Reuters.
Carradine's body was naked when it was found and there were no signs of other people in the room, Jantrapirom said. The body has been sent to a hospital for an autopsy.
Lori Binder, a representative for Carradine's Los Angeles-based talent manager, said the actor was in Thailand to shoot a film called "Stretch." She declined to give further details of his death while it was under investigation.
Carradine, from a family of performers and the eldest son of well-known character actor John Carradine, enjoyed a long career on Broadway, U.S. television and in movies such as director Quentin Tarantino's "Kill Bill: Vol. 1" and "Kill Bill: Vol. 2."
Born in Los Angeles, Carradine worked on Broadway before earning a spot on Hollywood's map in the 1960s in TV westerns such as "Wagon Train" and "The Virginian" as well as his starring role in a TV version of hit western movie "Shane."
But it was the role of Kwai Chang Caine, the wandering monk in "Kung Fu," that earned the actor his greatest fame.
The series aired on U.S. television starting in 1972 and immediately won a large base of fans of the half-Asian martial arts expert and student of life as he travelled through America's Old West.
The show spawned a movie and numerous other offshoots. Overall, Carradine's credits include more than 200 roles in movies, TV, video and DVD spanning nearly five decades.
His role as Caine in "Kung Fu" earned him a nomination for an Emmy, U.S. television's highest honour, and his turn as the villainous Bill in "Kill Bill: Vol. 2" led to his fourth Golden Globe nomination.
He also won critical acclaim for portraying folk singing legend Woody Guthrie in the Oscar-nominated 1976 film "Bound for Glory."
Carradine was married five times and had two daughters from previous marriages. His latest wife was Annie Bierman, whom he married in 2004. His brothers include the actor Keith Carradine.
(Additional reporting by Bob Tourtellotte in Los Angeles; Editing by John O'Callaghan)
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