The Wicked Witch of the North, named Mombi, is a fictional character in L. Frank Baum's Oz Books. She appears and is the main antagonist in the book The Marvelous Land of Oz and is alluded to in other works. Mombi plays a significant role in the fictional history of Oz.The character was originally presented as a lowly hag who had enchanted Princess Ozma in order to prevent her from ascending to the throne. Later in the series, L.