The Ghost Witch of Old Salem was the disguise of Arlene Wilcox's twin sister. Her disguise used makeup and battery-powered wiring to give her a glow. Appearing on Halloween night, as dictated by legend, she shocked the town with her similarities to Arlene. Convinced the witch had taken posession of Arlene, a mob went out to capture her, but they caught Scooby-Doo instead. Thinking her plan had succeeded, she raced back to the graveyard, where Fred Jones and the others had set a trap. When the trap caught Shaggy Rogers and Scooby instead, she ran off, but fell into the open grave that was being worked on when she first appeared. When the mob arrived, they realized the truth and relieved Arlene of guilt. She tried to make it look like Arlene had been possessed by their ancestor, Milissa Wilcox (whom had an uncanny resemblance to Arlene), because she hoped to drive her sister out of town and keep the family inheritance for herself. The 'witch' and her partner (who had built the suit) were subsequently arrested.