Navi the navigation fairy from OoT was pretty annoying too.
"Hey, listen! Hey, listen! Hey, listen! Hey, listen! Hey, listen! Hey, listen! Hey, listen! Hey, listen! Watch out!" :P

As for me....

Banjo (Banjo-Kazooie) How Kazooie could put up with this dumb stereotype of a bear is beyond me. Why couldn't Kazooie be the only main character of the game, so that she (and we) wouldn't have to put up with Banjo and his....crappiness? >_>

Bridget (Guilty Gear XX) I'm not a big fan of boys who dress like and act like girls, and look drunk/high in their character select screen portrait on top of it.

Ky (GG) He's just...boring. His play style, his dialogue, his win quotes, everything about him is plain.

Practically everyone from FF8 except for Raijin and Quistis for some odd reason.

Scumocide (Captain Commando) Just because of his name and his cheapness. A two-hit KO that hits in a large, nigh-unavoidable radius? No thank you, I think I'll go back to Final Fight 3 now, kthnx.

Balio and Sunder (BoF3) Just because they kept torturing poor little Ryu Hell, they almost (SPOILER)killed him later in the game, but luckily, his dragon power awoke at that time so he didn't die

My list after that would go ad nauseum, forever and ever and ever until after the end of time @_@