J.R. and ‘Dallas’ to Ride Into the Sunset : Television: CBS cancels the prime-time soap opera after 13 years. The final episode will air May 3.

“Dallas,” the long-running soap opera about a Texas oil family that helped define television in the 1980s and provoked an international guessing game over who shot J.R. Ewing, was canceled Wednesday. CBS said that it will have its final broadcast with a two-hour episode May 3.

Larry Hagman, who starred as the dastardly tycoon J.R.--and who was one of only two cast members, with Ken Kercheval, to be with the series for its entire run--was not surprised at the announcement, saying he had known for a couple of months that the show was ending.

“Thirteen years is not too shabby. Not many actors work that long,” Hagman said.

And what about memories?

“Blood, sweat, tears--no, no tears,” Hagman quickly corrected himself. “Laughs, lots of laughs. The 12 years with Patrick Duffy were wonderful, and with Linda (Gray), and the others . . . we had a great cast.”

Hagman said that he has several movies in the works that he plans to write, direct and produce, including a project on real-life Texas oilman H. L. Hunt.

“Dallas,” which premiered as a five-episode spring series on April 2, 1978, was television’s top-rated series for the 1980-81, ‘81-82 and ‘83-84 seasons, and finished in the Top 10 as recently as the ‘85-86 season. But its popularity has been declining in recent years. It ranks 60th among the 136 series that the four networks have broadcast this season.

“Dallas” ushered in an era of prime-time soap operas, including its spinoff, “Knots Landing,” which CBS already has renewed for a 13th season. Its success in serializing stories also was credited with helping set the stage for dramas such as “Hill Street Blues” and “L.A. Law.”

“Fourteen years ago, when ‘Dallas’ premiered on CBS, it turned the traditional one-hour dramatic format on its ear,” CBS Entertainment President Jeff Sagansky said in a statement. “It kept viewers on the edge of their couches by introducing the cliffhanger, and later created a national guessing game--and a Nielsen coup--with the question ‘Who Shot J.R.?’ ‘Dallas’ made a difference for CBS, and left a major mark on prime-time television.”

When the mystery of who had tried to kill J.R. was solved in the Nov. 21, 1980, episode, more than 300 million people watched worldwide, including an estimated 83 million Americans, more people than had voted in the presidential election less than three weeks before. It was the most-watched program in television history, attracting 77% of the audience watching TV at the time. The 1983 finale of “MASH” later topped the “Who Shot J.R.?” episode, but it remains TV’s second most-watched episode.

“Dallas’ ” final episode, the series’ 356th, will have a plot reminiscent of “It’s a Wonderful Life,” with Joel Grey portraying an enigmatic angel helping answer the question, “What would the ‘Dallas’ world have been like had J.R. never been born?”

Returning as guest stars will be Mary Crosby as J.R.’s ill-fated mistress and assailant, Kristin Shepard; Linda Gray as J.R.’s long-suffering ex-wife, Sue Ellen; Steve Kanaly as J.R.’s half-brother, Ray Krebbs; Ted Shackelford as J.R.’s younger brother, Gary, and Joan Van Ark as Gary’s ex-wife, Valene.

Although several dramatic series lasted more years than “Dallas,” CBS said that only one produced more episodes: “Gunsmoke” with 402.

Contributing to this story was Assistant Calendar Editor Aleene MacMinn.