In Hollywood, Pete Duel found work in television, making small guest appearances in comedies like Gomer Pyle, U.S.M.C. and dramas, such as ABC’s Channing with Jason Evers and Combat! with Rick Jason and Vic Morrow. In 1965, he was cast in the comedy series Gidget. Duel played Gidget’s brother-in-law, John Cooper, on the series, and appeared in twenty-two of the thirty-two episodes. Gidget was cancelled after only one season in 1966, but Deuel was immediately offered the starring role of Dave Willis, a newlywed apprentice architect, in a romantic comedy called Love on a Rooftop. Although the show earned good ratings, ABC decided not to bring it back after its first season. Duel wished to move from sitcoms to more serious roles. Around 1970, he also changed his name, dropping the “r” from Peter and the 1st “e” from “Deuel”. In the credits on the series Gidget, episode 25, his last name appears as “Devel”.  He appeared in The Psychiatrist, The Bold Ones, Ironside, and Marcus Welby, M.D.. He also made feature films during this time, beginning with the important role of Rod Taylor’s best friend and copilot, Mike Brewer, in The Hell with Heroes in 1968 and the next year in Generation. Following that film, he went to Spain to film Cannon for Cordoba (1970), a western in which he played the mischievous soldier, Andy Rice.

In 1970, Pete Duel was cast as the outlaw Hannibal Heyes, alias Joshua Smith, opposite Ben Murphy, in Alias Smith and Jones, a light-hearted western about the exploits of two outlaws trying to earn an amnesty. During the hiatus between the first and second seasons, he starred in the television production of Percy MacKaye’s 1908 play, The Scarecrow. In the early hours of December 31, 1971, Pete Duel died at his Hollywood Hills home of a self-inflicted gunshot wound to the head. Duel’s girlfriend, Dianne Ray, was at his home at the time of his death and discovered his body. Ray later told police the two had watched Duel’s series Alias Smith and Jones the previous evening. She later went to sleep in another room while Duel stayed up. Sometime after midnight, Duel entered the bedroom, retrieved his revolver and told Ray “I’ll see you later.” Ray then said she heard a gunshot from another room and discovered Duel’s body. According to police, Duel’s friends and family said he was depressed about his drinking problem. He had been arrested and pleaded guilty to a DUI accident that injured two people the previous June.[9] Duel’s death was later ruled a suicide.