Ron Palillo, best known for his role as Horshack on "Welcome Back, Kotter," died this morning at his home near Palm Beach, FL from an apparent heart attack. He was 63-years-old.

According to TMZ, Palillo was found around 4AM by his partner Joseph Gramm. The report indicates that Gramm called an ambulance and Palillo was rushed to the hospital, where he was pronounced dead.

While "Welcome Back, Kotter," appeared to be in good health at the time of his death, one of Palillo's colleagues at G-Star School of the Arts told TMZ that he was a heavy smoker and had been suffering from a bad cough. Palillo was even scheduled a doctor's appointment for today, according to the source.

Palillo's claim to fame on the show involved calling out, "Ooh ooh ooh, Mr. Kotter" as one of the Sweathogs on the show. He appeared on the show with John Travolta from 1975 to 1979.

After "Kotter," Palillo appeared in "Laverne & Shirley" and voiced a character on the Disney cartoon, "Darkwing Duck."

Palillo's "Kotter" co-star Robert Hegyes, who played Epstein, also passed away earlier this year after suffering a heart attack, according to reports.

Welcome Back, Kotter Arnold Horshack Raising Hand