Gabby - played by Shelley Duvall, is the most beautiful member of the witch coven in Casper Meets Wendy. She is apparently based on Velma from the Harvey Comics stories.
Gabby is boy-crazy, extremely ditsy, and also unbearably stupid to the point where she has to rely on magic for almost everything (i.e. Tying her shoelaces, reading algebra, brushing her teeth and playing the glockenspiel). True to her name, she has a habit of being a “motormouth” and making references to popular music artists (of the time) such as Madonna and the Spice Girls. Her primary color is blue: with the ability to make similar outfits with that color. As a witch she also possesses uncharacteristically-refined, yet expertise knowledge of chemistry, in general, as she has no problem assisting Gerti with her potions.