Every one of the 'peppy' girl characters from Final Fantasies. They bring this same tired character back every time and then make her worse.
Selphie, then Eiko (who while annoying, was only 6, so she acted her age), Rikku, and ugh, I want to strangle Vanille so far.
It was laughably bad with Rikku who was described in the manual as the bubbly/cheerful stereotype and then she did nothing but whine.
Everyone hates Hope but, apart from his stupid name, I haven't found him that bad. He's a kid trying to deal with his life falling apart. I haven't seen anything past chapter 7 yet though. (Ooh, this was an upbeat first post)