Larry Hagman, who spent more than a decade playing TV villain JR Ewing has died at the age of 81, his family says.
Hagman, who had suffered from cancer and cirrhosis of the liver, died in hospital on Friday afternoon, according to a family statement.
"Larry was back in his beloved Dallas, re-enacting the iconic role he loved most," said the family. "He was surrounded by loved ones."
Long-time friend Linda Gray, who played Sue Ellen, was by his bedside.
"Larry Hagman was my best friend for 35 years," said Ms Gray in a statement released by her agent.
"He was the Pied Piper of life and brought joy to everyone he knew. He was creative, generous, funny, loving and talented and I will miss him enormously.
"He was an original and lived life to the full."
Original cast member Victoria Principal, who played Pam Ewing, said Hagman had been "bigger than life, on-screen and off".
"He is unforgettable, and irreplaceable, to millions of fans around the world, and in the hearts of each of us, who was lucky enough to know and love him."
During 13 years as the most scheming oil tycoon in Dallas, JR in his Stetson became one of the most distinctive faces on television screens across the world.
It quickly became one of the network's top-rated programmes - with its 356 episodes being seen by an estimated 300 million people in 57 countries - and was revived this year.
Five bottles of champagne
Born in Texas, Hagman later moved to Los Angeles where he was cared for mainly by his grandmother.
After a brief period spent working in the fields, Hagman followed his mother - stage and screen actress Mary Martin - into showbusiness and even toured and played in musicals with her.
Moving into television, he played astronaut Tony Nelson in the 1960s television comedy I Dream of Jeannie.
He first performed as JR Ewing in 1978 and became its highest-paid star, as the programme came to define 1980s excess.
The actor himself owned more than 2,000 cowboy hats, his character's trademark.
When Dallas finally finished in 1991, Hagman went on to appear in hit films Nixon and Primary Colors.
His forthright biography, Hello Darlin', detailed his youthful drug-taking exploits and revealed the extent of his 50-year battle with alcoholism.
Even on the hardworking set of Dallas, he consumed five bottles of champagne a day for years and was finally diagnosed with cirrhosis of the liver in 1992.
Three years later he had a liver transplant and kept a photo of the organ donor above his mirror.
"I say a prayer for him every morning," he said.
Despite this, Hagman continued to drink secretly until a further life-saving operation in 2003 forced him to stop.