A shitton of characters come to mind, so in no particular order:
Slippy Toad (Starfox series): You know, I don't really care if you show me the boss's health while alive, I don't want to protect your danger-prone, androgynous, froggy ass.
Navi (Legend of Zelda: Ocarina of Time): I appreciate the lock-on feature and your advice, but your voice is annoying and nobody needs to be taught how to open doors.
Desmond (Assassin's Creed series): You have no personality whatsoever. I don't care about you, and the fact that you couldn't even run in the first game pissed me off so much.
John Madden (Madden series): Not exactly a character, but shut up. All he does is state the obvious. Even after he was removed from the commentaries of the Madden games, his successors have done the same.
Big the Cat (Sonic Adventure, Sonic Heroes): Mental retardation is not funny, and you are going to hell for trying to make it funny Sonic Team.
The entire Animal Crossing cast (duh): You look creepy, you speak in gibberish, and you have no understanding of property ownership. K.K. redeems himself with his awesome music, but the rest of you are worthless.
Kratos (God of War series): You are nothing but a cess-pool of rage and violence and you lost all sympathy from me once God of War 2 started. You're not tragic anymore, you're just disgusting.
Princess Peach (You should know this *****): You are retarded for continually allowing yourself to get captured. One would think a princess would invest in some bodyguards. Wait a minute, didn't you fight in Mario 2, Super Mario RPG, Paper Mario, Super Paper Mario, and Super Princess Peach? Not to mention the Smash Bros games. Why the hell aren't you resisting capture?
Mario (If you don't know who this is, you shouldn't be on this site): Any man who allows himself to be Peach's ***** is not a man at all. You have no personality whatsoever. You are a plot device, nothing more.