Ron Palillo on "Welcome Back Kotter" Credit: Courtesy Everett Collection

Welcome Back, Kotter actor Ron Palillo died Tuesday morning of a heart attack at home near Palm Beach, Florida, TMZ reports.

Palillo, who played Horshack on the series costarring a young John Travolta during its 1975 to 1979 run, was 63.

According to TMZ, Palillo was discovered by his longtime partner Joseph Gramm early Tuesday morning; he was rushed to the hospital and pronounced dead. A heavy smoker, the star was said to have been in good health in the weeks leading up to his unexpected passing.

After his stint on Welcome Back, Kotter, Palillo appeared on Laverne and Shirley and voiced a character on the animated Disney series Darkwing Duck, with dozens of additional TV and film credits to his name.