Ducky Duck, for just being an idiot
Furdle, for being an egotistical richardwad that never cares about others
EDIT: Kearn, for never listening to rational logic
All of the 9-year-olds that don't understand basic English
That's about all I can think of that I hate too much, and even then they're tolerable. Zeblote and Mr. Nobody can be unnecessarily negative at times, but I never really hated them that much.