The actor died at his home in West Palm Beach, Florida on Tuesday morning (14Aug12), according to TMZ.com.
No further details were available as WENN went to press.
Palillo graduated from the University of Connecticut before embarking on a career in entertainment, landing roles on U.S. TV shows Laverne and Shirley in the Army and Darkwing Duck.
He was perhaps best known for playing high school student Arnold Dingfelder Horshack on the popular American sitcom Welcome Back, Kotter, which featured a young John Travolta, but he was also a children's book artist and a teacher at his alma mater.
He additionally appeared in several New York theatre productions, including the drama Who's Afraid of Virginia Woolf? and the musical Guys and Dolls.