John Travolta Pays Tribute To 'Welcome Back, Kotter' Co-Star Ron Palillo

John Travolta has expressed his grief over the loss of his former Welcome Back, Kotter co-star Ron Palillo, calling him a great talent and "a wonderful person."

The actor passed away of an apparent heart attack at his Palm Beach Gardens home in Florida on Tuesday morning, aged 63.

His sudden death prompted many fans of the hit sitcom, in which Palillo played nerdy high school student Arnold Horshack, to recall their love for the series online, and now Travolta, who shared the small screen with the star for five years, has paid tribute to his late pal.

A statement from the Saturday Night Fever star reads, "Ron was a wonderful person and talent. And helped catapult Welcome Back, Kotter to great success. We will miss him."

Palillo is the second star of the popular program to die this year  - Robert Hegyes, who played tough guy Juan Epstein, passed away in January.