i hate larxenne from kingdom hearts chain of memories she is a total sadist and her laugh and she i just hate her so much

The first post matches my sentiments exactly! And I think the general posts about escort missions captured my runner up. I'll add one I don't think I've seen in the prior posts.

1. Navi (Zelda: OoT)
2. Natalya (Goldeneye 007: N64; all escort missions)

3. Baby Mario (Super Mario World 2)
Remember the sound of his crying you hear every time you get hit? No wonder Yoshi was busy eating fuzzies!

Jogurt from Shining Force is pretty annoying.  Plus he never levels up.  He is among the least useful characters in a game, ever...except for comic relief.

http://shining.wikia.com/wiki/Jogurt

I have to say, the most annoying Video Game character is not Navi. The most obvious choice is freaking Bubsy Bobcat! The first Chapter, Cheese Balls of Doom, every time you die, you hear this satanic catchphrase: What could possibly go wrong?

    The most annoying character in a video game is Porky Minch In the Earthbound Series. Porky was a big crybaby, and you had to saved him in Mother 2. Then, out of nowhere in Mother 3, he became the most hated character by killing your protagonist's brother and mother.

Well the most annoying would have to be Metapod or shuckle because they take so very long to take down.

I swear, before even reading your post, I KNEW you were going to say Navi (based on the title) XD. Well, guess what? I agree . "Hey, look, listen" is driving me insane (unless I already am), and it is agreeable that Navi from The Legend of Zelda is the most annoying video game character ever.

Amy Rose. I liked her okay in Sonic CD, but other than that, she's been clingy and loud.

Ashley Graham from Resident Evil 4 just standing screaming "help me Leon" as if he hasn't got enough to deal with and she makes every task in that game longer and harder than it needs to be

The most annoying character is Wario from Mario. The Mario universe is infinite, but Wario is still a waste of space. He deserves to die for his disgusting, creepy qualities. Uggh.

I find princess peach to be very annoying. She is always getting captured by bowser and she can never defend herself for once.  I find everything about her annoying, her voice, the way she talks, her patheticness, and how much she demands. Those are just some reasons I don't like her and Ifind her annoying. The stuff mario puts up with. You'd think with the moves she has in smash bros,she would be able to defend against an oversized turtle. Guess not.

Strangely I never found the most typical responses (Navi, Slippy, Tingle etc.) that annoying. Maybe it's because they do offer you some help - minor it may be - and  aren't really feeling that grandiose about their skills or bossing you around (Navi being maybe the exception).

The one character that really p****s me off is Sofia Lamb from Bioshock 2. 
She is constantly babbling about how her schemes will bring peace and goodwill to earth while treating people (including her own daughter) like subjects in test. All this while having the smuggest, most irritating sound possible. Every time she comes on screen I felt like I'm listening to person with really idiotic world-views without being able to debate or do something about it, other than keep playing  and waiting for the sweet, sweet moment of retribution.
But here's the two things that really make her the absolutely most despicable person I've seen in a video game
SPOILER ALERT

1) She makes one of your long-term allies into Big daddy, forcing you to practically euthanize him, all the while declaring how you don't understand the good that comes from her constant manipulation of peoples will.
2) If you play the game with moral character (like I did) she never gets what she deserves in the end. I really wanted to see her having some delightfully ironic punishment, but in the end you die and she lives.

SPOILER ALERT ENDED

Now to be fair game developers probably meant her to be as annoying as possible, to which I can only reply:
MISSION F*****G ACCOMPLISHED.

Angry rant over.

I hate Vi from Skyward Sword. She nevers really gives you any advice or anything useful, unlike Midna, and she justs pops up whenever to annoy you.

Cat sith in Final fantasy VII. Roman and Brucie in GTA IV. The AI-controlled fellow Lost-members in GTA IV: lost and the damned Gang war missions. The dog in Duck Hunt. All opponents after Major circuit in Punch Out. Princess Peach/Toadstool. Pikachu. All the kids in Skyrim. The puppy in Dont kill the puppy.

I am sure I could think of more.

navi,creeper,villager,daisy,tatl. most annoying,NAVI

"All you had to do was follow the damn train, CJ." and "I could use a little help here, Tommy."

Zidane in Final fantasy IX, he annoys me so much and it sucks that you have to use that monkey all the time... When I play with my friends or with my brother I always tell them that they fight with that useless piece of shibadaba who can't even steal properly and most of his abilities are useless, and his trance moves are all the same shiet in a different package..

And then there is mother from soulsilver/heartgold, because she keeps calling you all the time and gives you lot of useless berries that your not even going to use in the whole game..

There is lot of more annoying characters, but can't right now think any more than those two a$5holmes.