The late Larry Hagman will make his final appearance as J.R. Ewing on “Dallas” tonight. The death of the show’s defining character poses challenges for TNT, which has placed a big primetime bet on this revived series. 

J.R. was the TV villain an entire generation of Americans loved to hate. 

“We all knew what he would be when he came back, evil. But reptilian-ly, charmingly evil,” says Deadline Hollywood reporter Dominic Patten, who writes about TV and TV ratings.

He says season one of the new “Dallas” opened with a bang last June, drawing 6.9 million viewers an episode. But in season two, which started early this year, the audience has fallen by 60 percent. It’s partly timing, according to Patten.

“Debuting a show in the summer is a lot different than debuting a show in January,” he says. There’s not a lot going on in the summer TV-wise, but in January, “they’re bringing “Dallas” back when the Super Bowl and reality shows were all at full force. That’s a hard game to win.”

He also says the current season has gotten less marketing oomph from TNT, partly because TNT had already pulled out all the stops for the initial return of the series. Also, the company may have been sensitive about advertising right after Hagman’s death.

Brand strategist Adam Hanft says the show might bring back more actors from the original series to drum up some buzz. But he expects regular “Dallas” viewers to keep tuning in even after the show lays J.R. to rest.

“It’s a big void, but people who really love this show, really love this show, and there’s some tolerance built in,” Hanft says. “It’s not like the writers and producers killed him off,” causing a viewer backlash. “Here, the fans know something happened that nobody could control, so fans will give a hall pass for a while to see what emerges.”

J.R. Ewing is gone, but the show he made will live on — at least for now.