|This needs a stretch.|
The Ghost of Dr. Van Helsing was the only fake monster at Dracula's Halloween party.
The New Scooby-Doo Mysteries
He was a disguise of Igor, helped by Chandra, to drive the monsters out of the castle. Igor thought he could take over and be as messy as he wanted, but he wasn't counting on the hidden motives of Chandra to gain more magical power and take over for herself. (A Halloween Hassle at Dracula's Castle)