The actor best known as the nerdy high-school student Arnold Horshack on "Welcome Back, Kotter," has died in Florida.

Ron Palillo was 63.

Palillo's friend, Karen Poindexter, says Palillo died early Tuesday in Palm Beach Gardens of an apparent heart attack.

Palillo was forever remembered for the character he played from 1975 to 1979 on the ABC sitcom: a nasally Brooklyn teen whose hand shot skyward and who barked out a string of "Ooohs" when a teacher posed a question.

Though his co-star on the show, John Travolta, went on to fame, Palillo struggled to expand beyond his role as Horshack.

Of Horshack, Palillo once told an interviewer from the Birmingham News: "While I loved him, I really loved him, I didn't want to do him forever."