 Gabe Kaplan (qv) and John Travolta (qv) both left the show after  the third season. Kaplan left over creative differences with  James Komack (qv). Travolta left after the massive success of  _Saturday Night Fever (1977)_ (qv). Kaplan appeared rarely in the  final season but his name was still featured in the opening credits  as being the star of the show. John Travolta (qv) appeared  occasionally in the final season. When he did appear he was listed  as "Special Guest Star".