Especially when he starts feeling sorry for himself and spends the next few hours of cutscenes whining.

Lol yahhh worst emo breaksown ever DAAMMMMMNNNN IIITT!

"Let me handle it!"

Noooo Slippy you fucking fucktard noooooooo!!!

I think some of these fail because they are just a minor role and are probably meant to be annoying. (example in OP included, although the thread/topic is full of win...)

I don't think this would be rated as number one as there have been some great examples, but I'm surprised no one mentioned Emil from Tales of Symphonia Dawn of the New World yet.

I agree with jlauro, I find it most annoying when a badly voice character is at front and center. Like Emil in ToS2 and Beat, Polka, and Frederic in Eternal Sonata. Those would be my picks.

Wendee Lee. She was Nan in Tales of Vesperia. Her voice AND character was so whiny and childish IMO.

One of the best features in Baten Kaitos was the ability to turn of voices. That says a lot of the voice acting...
The scene were Tidus and Yuna laughes in FFX are the most disturbing scene in a video game ever. I have never been so scared and at the same time so embaressed.

Did I see someone mentioning Pikachu? Ahem. Pikachu, I choose you!

pretty much every voice in every dialogue-heavy game, that doesn't let you skip conversations!

like Monkey Island SE

Tidus' voice is really annoying, and that laughing scene was really embarrassing that I had to put the volume in 0 in order to not hear those creepy laughters.