Jacqueline Stander, an agent for Palillo, told NBC News that the actor had a heart attack and passed away in his sleep.

Palillo starred as Horshack, the goofball of the high school group known as the Sweathogs on the hit series. The show aired from 1975-79 and featured a young John Travolta as Vinny Barbarino.

Actor Robert Hegyes, who played Epstein on the show, died on Feb. 26 at 60. 

In a story on its website Tuesday, the Palm Beach Post quoted Stacy Sacco, a friend of Palillo’s. “He just couldn’t have been more fun and intelligent or talented. He was an amazing human being.” The newspaper said Sacco met Palillo 20 years ago when he was a guest on Ellen DeGeneres’ sitcom in Los Angeles, on which Sacco was a script supervisor. “I had been a fan. We all knew who he was. He was a shining star,” Sacco said.

Palillo was born on April 2, 1949, in Cheshire, Conn. He had been teaching acting classes at G-Star School of the Arts, a charter school in Palm Springs, Fla., for about three years, according to the Palm Beach Post report.