Actor Ron Palillo, who is best remembered for his role as Arnold Dingfelder Horshack on the classic ABC sitcom Welcome Back, Kotter, passed away this morning in his Palm Beach, Florida home at the age of 63.

He is the second "Sweathog" to pass away this year: Robert "Juan Epstein" Hegyes died on January 26th.

TMZ reports that Palillo, a heavy smoker, died of an apparent heart attack.

Though known mostly for playing class clown Arnold Horshack, Palillo was also a noted stage player, appearing in productions of Amadeus, Who's Afraid of Virginia Woolf?, and Guys and Dolls.

Later in life, Palillo became an acting teacher at the G-Star School of the Arts for Motion Pictures and Broadcasting.

"You don't see any Sweathogs in my class," Palillo told USA Today in 2009. "They haven't done this yet, but I'm waiting for the 'Ooh ooh ooooooh!'" — a reference to his Welcome Back, Kotter catchphrase.

Palillo is survived by his longtime partner Joseph Gramm.

[photo via AP]