Ron Palillo, the class clown from "Welcome Back, Kotter," has died. The actor best known as Arnold Horshack from the 1970s sitcom was 63. TMZ reports the cause of death was a heart attack.

According to TMZ, the actor was having difficulty early in the morning. His longtime partner, Joseph Gramm, a retired actor, called 911. The star was rushed to Palm Beach Gardens Medical Center by ambulance where he was pronounced dead.

Palillo was best known for his role as a "Sweathog" at the remedial high school in the comedy. The University of Connecticut grad spent the last three years of his life teaching acting at the charter school G-Star Academy.

The site Gossip Extra notes that Palillo moved to the gated community of Mirasol when he started teaching at the West Palm Beach charter school for students interested in TV and movies. The site adds that the star fell in love with the area after he performed in a play.



[Photos: More TV Stars We've Lost in 2012]







Palillo struck up a friendship with the charter school G-Star founder Greg Hauptner and eventually taught there. Hauptner noted the star had suffered from whooping cough and his "health wasn't the greatest." He recalled, "He was a fantastic teacher. The kids adored him. They'd find old recordings of 'Welcome Back, Kotter' and watch Ron. The kids are coming back to school next week. They're going to be crushed."

The sitcom that aired originally on ABC starred a group of remedial students, including John Travolta, who weren't the brightest class, but certainly the funniest. Palillo played Arnold Dingfelder Horshack, best known for calling out "Ooh! Ooh, ooh!" in class.



Watch the cast of "Welcome Back, Kotter" reunite at last year's TV Land Awards:









Palillo had roles post-"Kotter" in "Laverne and Shirley," voiced the animated Disney show "Darkwing Duck," and made many appearances on hit TV shows from "The A-Team" to "Love Boat."