LOS ANGELES -- Dennis Hopper leaned back in his chair, eyes partly masked by glasses, and smiled at the thought of playing a "straight" character in HBO's "Doublecrossed" (Monday at 9 and Thursday at 11:35 p.m.).

Hopper, the mellowing one-time bad boy of the movies, portrays drug smuggler Barry Seal, who was shot to death in Baton Rouge, La., five years ago after testifying against Colombian drug lords.

"I get to play a straight guy for a change," said Hopper.

Still, Seal is not a typical straight character. "He's a criminal, but he's not a psycho. He's got a touch of class. He didn't drink or take drugs," Hopper said.

"It gave me an opportunity to play a man who wasn't crazy. He was on the edge, he was a loudmouth, he thought nothing could touch him."

Hopper plays Seal as a man who gets high living on the cutting edge of catastrophe -- first as a smuggler, then as a government informant who courted death to get photographs and evidence against his former bosses. Seal refused offers to join the federal witness protection program.

The movie contends drug dealers learned Seal was an informer when Lt. Col. Oliver North used pictures of drug dealers with Sandinista officials to persuade Congress to vote funds for the Nicaraguan Contras.

"Doublecrossed" also stars Robert Carradine as a drug agent, G.W. Bailey as Seal's copilot and sidekick, and Adrienne Barbeau as his wife, Debbie. Roger Young wrote the screenplay, from a story by Young and Alex Lasker, and directed the film in Louisiana and Puerto Rico.

Seal was a 747 pilot for TWA until he was fired when he was caught attempting to fly guns to Mexico in a government sting. Under the cover of selling airplanes in South America, he began flying drugs into this country.

Hopper, who was recently seen in the Showtime movie "Paris Trout" as a small-town Southern bigot and demented killer, says he preferred "playing Barry Seal to Paris Trout. I had more fun watching it. It's an adventure story. It hits a lot of levels."

When Hopper directed "Easy Rider," a 1960s paean to alienated youth and the drug culture, Seal owned the helicopter used in the aerial shots in Louisiana. His brother, Ben Seal, flew the aircraft.

Hopper believes that "Easy Rider," which also starred Peter Fonda and Jack Nicholson, popularized cocaine in this country.

"There wasn't a cocaine problem before 'Easy Rider,'" he said. "We smoked grass throughout the movie, but the way we made our money was selling cocaine we got in Mexico. Nobody had thought about smuggling it before that. I picked it because we couldn't smuggle marijuana on the bikes and heroin had a bad reputation. Cocaine was the drug of kings. I didn't think it was addictive at the time."

Hopper, whose career was nearly wrecked by drugs and alcohol, says he has been clean for the past eight years.

"Let me tell you cocaine will drive you crazy. It did it to me. I was institutionalized. I was locked up. My life was unmanageable. When I got out I got the idea alcohol was my problem. I didn't drink but I used cocaine and went crazy again. I almost didn't come out of it that time. Don't let anybody tell you cocaine won't drive you crazy."

Hopper drinks a nonalcoholic beer during the interview near his home in the coastal Venice area of Los Angeles. "I loved beer," he says.

He was just back from a trip that took him to the Cannes Film Festival in France, to Portugal for its film festival and to Japan to model clothes for a Japanese designer.

Hopper got his start as an actor opposite James Dean and Natalie Wood in "Rebel Without a Cause." He was in "Giant" and "Gunfight at the O.K. Corral." His battles with director Henry Hathaway during the making of "From Hell to Texas" led Warner Bros. to drop his contract. He moved to New York, where he studied acting with Lee Strasberg and worked in live television.

His work in independent pictures culminated with the huge hit "Easy Rider," but his first movie for a big studio, "The Last Movie," ended in a fight for creative control and the movie received only limited release.

Hopper emerged from obscurity for a featured role as a drug-crazed photographer in "Apocalypse Now," but then his career faded again.

Hopper did not surface as a leading actor until "Blue Velvet" in 1985, and since then he has been on a roll.

But as "Doublecrossed" indicates, Hopper continues to be drawn to dangerous roles. He will direct himself in the upcoming "Spirit Moves," in which he will play a serial killer who is a psychic. And in another upcoming film, "Midnight Heat," he will play a psychotic drug dealer.