Cassidy Wiliams was a member of the original Mystery Incorporated, along with Brad Chiles, Judy Reeves, Ricky Owens and their parrot Professor Pericles. Cassidy loved Ricky and wrote about him in her diary. On one mystery involving the Freak of Crystal Cove, her gang were blackmailed by Pericles into splitting up and leaving town. Many years later, Cassidy returned and the alias Angel Dynamite, working for Ricky who went under the name Mr. E. She is also became a radio presenter.They helped the second Mystery Incorporated (Fred, Daphne, Velma, Shaggy and Scooby) out numerous times, with Cassidy growing fond of them and worrying that Pericles, who had escaped an animal asylum, would hurt them. When the second Mystery Inc split up due to the Freak being unmasked as Mayor Jones, Fred's dad, Cassidy quit working for Mr. E and went back to her old name. Months later, when the second Mystery Inc were back together, they didn't trust Cassidy for lying about her identity but came to see if she was okay after a robot blew up her radio station.Cassidy joined the second Mystery Inc in a journey underwater the find where the robots were coming from. They learnt Pericles had an entire faculity with hundreds of killer robots deep underwater. During an escapade involving the group attempting to escape, Cassidy vowed to stay behind and open the gates so their sub could escape. The sub successfully escaped, but the faculity self-destructed and Cassidy did not survive.In the post-Nibiru timeline, she was alive and married to a much more healthy and successful Ricky. Show less «