A Pup Named Scooby-Doo (1988)

S1E6 The Babysitter From Beyond

Scooby and Shaggy head out to catch a frightening movie after leaving Shaggy's baby sister with a sitter. However, they are taken aback by the sitter's ghastly appearance. To make matters worse, the terrifying creature from the film seems to have come to life, and an escaped convict is on the run nearby.