Hanna-Barbera Scooby-Doo...Mystery Comics #21

After watching a classic horror film festival, Fred remarks that Winston Shocket was the greatest actor of the genre. A stranger offers to introduce the gang to the now-reclusive actor. At an abandoned theater, the stranger reveals himself to be Shocket, who is planning a comeback. The next day, the gang hears a report of a mummy terrorizing people.