Scooby-Doo, Where Are You! (1969)

S01E10 Bedlam in the Big Top

The crew comes to the aid of two circus performers who reveal they've abandoned the circus due to a string of bad omens. The ringmaster shares unsettling tales about a figure known as 'The Ghost Clown,' who is believed to be behind the bizarre mishaps and eerie occurrences plaguing the circus.