Ron Palillo -- who was best known for playing the loud-mouthed high school student Arnold Horshack on the 1970s TV series Welcome Back, Kotter, has died at age 63.
Several sources reported that the actor passed away Tuesday morning at his home in Palm Beach Gardens, FL.
Palillo had taught classes at the West Palm Beach charter school G-Star Academy as recently as 2009, according to the school's founder and CEO, Greg Hauptner. Prior to that, the actor lectured in colleges and high schools across the country.
Welcome Back, Kotter starred Gabe Kaplan as a compassionate high school teacher who returned to his inner city neighborhood to teach a new generation of troubled kids -- one of whom was portrayed by John Travolta.