Six years after their first live-action series ended, The Addams Family returned, guest-starring on The New Scooby-Doo Movies.
The episode, "Wednesday is Missing", was a back-door pilot for the Addamses' next series, the first of two animated incarnations that would bow the next year, albeit on NBC instead of CBS. John Astin reprises as Gomez, but would be replaced by Len Weinrib the following year. Never fear, when the series was revived in 1992, Astin was brought back as Gomez. Carolyn Jones, Ted Cassidy, & Jackie Coogan also returned for this one.
I don't know why NBC got the animated Addams Family, which we reviewed a ways back. It's just one of those things.