The original Mystery Incorporated are a group of missing kids from Crystal Cove.
Pictures of them were seen in a Crystal Cove High School yearbook.
Their mascot, Professor Pericles was found in Crystal Cove's Animal Asylum.
In Where Walks Aphrodite, Professor Pericles found Scooby and they both teamed up to stop Aphrodite's Ghost.
Velma Dinkley suspected that Angel Dynamite was actually Cassidy Williams because she had the diary of Cassidy Williams and she knew alot about Crystal Cove's most top secret mysteries, yet she hadn't been in town for a very long period of time according to Velma.