Antagonist
Character Role Analysis
Wizard of Reckoning/Mad Cow Disease
This one gets a bit tough. Our story doesn't really have a clear villain; it's not like Superman and Lex Luthor, or Dorothy and the Wicked Witch of the West. Sure, there are the guys from United Snow Globe Wholesalers and the fire giants, but they're small potatoes. Instead the antagonist is the mad cow disease that Cameron is fighting against, which is personified in the Wizard of Reckoning.
See, throughout the book the Wizard of Reckoning is depicted as this mysterious, dark creature too frightful to accurately describe—but then in the end he reveals himself to actually be Cameron. Well, more like Bizarro-Cameron. When this happens, we realize that Cam's been fighting himself this whole time, railing against the disease that is slowly eating away at his brain.