But his wife persuaded him to give the role of conniving oil baron and cattle rancher J.R. Ewing a shot, saying they could "renegotiate" and that the job might pay off.
It did, eventually earning Hagman a reported $100,000 or more per episode. And now fans from across the world are paying as much as $1,000 apiece to celebrate the 30th anniversary of the debut of what became one of the most popular prime-time soap operas in TV history.
"People are crazy," Hagman said Thursday. "I guess it's a TV show people identify with."
On Nov. 8, J.R., Bobby, Sue Ellen and other Ewing kin will mark the anniversary with a reunion and barbecue at Southfork Ranch. Viewed panoramically in the show's introduction, the ranch is in the Dallas suburb of Parker, about 25 miles north of the flashy downtown skyscrapers also featured in the opening scenes.
Fans from Japan, Australia, Europe and across the United States have plunked down anywhere from $100 to $1,000 for the tickets. The more one pays, the greater one gains access to cast members including Hagman, Linda Gray and Patrick Duffy.
"This thing is going to be a lot of fun," said the 77-year-old Hagman, seated in the formal living room of the Southfork mansion, a trademark cowboy hat on his head. "It's the first one we've ever done with fans. They're coming from everywhere."
Along with the barbecue, there will be country music, dancing, fireworks and a laser light show.
"This is a chance to live like and be a Ewing for a day," said Jason Hardison, the event's executive producer. "We're going to celebrate the excess and success of the 1980s, at least the oil boom, and the money that surrounded Dallas."
Given the various story lines and characters in each hourlong episode, Hagman said he saw Dallas as more of a cartoon and "had fun with it."
Hagman, who grew up in Weatherford, west of Fort Worth, said he patterned J.R.'s twang, persona and family views after a businessman he worked for in high school who supplied oil drilling equipment.
But those close to Hagman say he's the antithesis of the scheming, arrogant head of the wealthy but dysfunctional Ewing clan.
Hagman, a former vegetarian and outspoken nonsmoker who gave up alcohol after his 1995 liver transplant, is now an avocado farmer. He and Maj (pronounced MY), his wife of nearly 54 years, rise with the sun and are often asleep by 7:30 p.m.
Their 44-acre spread in Ojai, Calif., is all-organic. Their home runs on solar power, which Hagman said knocked their electric bill from $40,000 a year to $13.
He remains close to a few "Dallas" cast members, hunting and fishing with Duffy, aka brother Bobby, each month. And he and Maj often dine with Gray, who played his trophy wife on the show.
Maj Hagman recalled that when her husband first got the "Dallas" script, he was out of work. The couple were in New York, where Hagman's mom, actress Mary Martin, was doing a show with Ethel Merman.
He was busy reading a script for a half-hour comedy while Maj reviewed the "Dallas" proposal.
"Woo! Larry, this is it!" she shouted. "There's not one redeeming character in the whole show."
She said it was right down his alley.
"But Maj," he replied. "The money is terrible."
She said: "We'll renegotiate."
After the "Who shot J.R.?" cliffhanger that concluded the 1980 season, when it was unclear whether J.R. would live, Hagman bargained hard with producers and landed a huge raise.
"That's chutzpah," Hagman said, explaining that the writers could have easily killed off his character. "But I made millions and they made billions. Everybody did well."
Today, Hagman said the question people most often ask him as a conversation opener is, "Who shot you, J.R.?"
When he tells them it was Bing Crosby's daughter, Mary, who played his sister-in-law and pregnant mistress on the show, they say, who is Bing Crosby?
"It's a different generation," Hagman said.