Luke fon Fabre from Tales of the Abyss. I cringed every time he talked in the game.

HEY LISTEN! TINGLE TINGLE KOOLOO-LIMPAH! BACKSLASH! AIRSLASH! I'M FEELING IT!

"Caps for annoyance"

XDDDDD

It's Reyn time is fucking cool, though. 

Hope and Snow in FFXIII

Almost everyone in FFX

Xion in Kingdom Hearts

Tatsu in Xenoblade Chronicles X

Konami, as a company, in life, in general

That money-grubbing, foppish pedophile Tingle.

Also, Prince Tricky from Starfox Adventures. 

Hahaha I can understand why some people hate Navi, but Tingle is so weird that I have to like him xD and... I must confess that he says kololim...PAH! I repeat it XD so you probably would hate me as well hahaha

The character I hated the most in Xenoblade was Sharla, god I hated her (and her voice) so much that I couldn´t have her in my team. Just listen to this:

Since no one else is going to mention him:

Otis, from Dead Rising.

Lamar from GTA V. Can't stand this character at all. Useless, getting Franklin in more trouble and inconveniences.

And Sweet from GTA San Andreas. He's very whiney towards CJ just because he wanted to look a life out of the 'hood.

To be fair with Sweet, CJ left a lot of unfinished business.

Most of Final Fantasy 13s cast lol

Fi. I'm sure there are more annoying characters than her out there (primarily in JRPG's, which have a long history of annoying me) but of the games I've actually played no one holds a candle to her. Navi is like five percent as annoying as Fi. Fi makes the game nearly intolerable.