Vacation curse strikes again - Ooooh ooooh! Horshack is dead. From TMZ... Ron Palillo -- the actor who played Horshack on "Welcome Back, Kotter" -- died this morning at his home near Palm Springs. He was 63. The details surrounding Palillo's death are unclear. Palillo was known for calling out, "Ooh ooh ooh, Mr. Kotter" as one of the Sweathogs on the show ... which he appeared on with John Travolta from 1975 to 1979. After Kotter, Palillo appeared in "Laverne and Shirley" and voiced a character on the Disney cartoon, "Darkwing Duck." Palillo's "Kotter" co-star Robert Hegyes -- who played Epstein -- passed away earlier this year after suffering a heart attack.