Doumon from the Tamers Forever Series is a manipulative, condescending and arrogant bitch who casually dissmisses Takato as a threat, treating him like a small child who needs to learn his place. Which makes it all the more satisfying when Takato calmly points out to her just how completely and utterly screwed she is.
Queen Of All Oni: Lung sees himself as the next Daolon Wong, and is utterly convinced of his brilliance and power. And yet, when his plan to break Jade to his will fails, he simply blunders ahead with it, even when it's clear he's killing her. This get him killed by her vengeful bodyguards.