rosalina .. and I don't like that they include her in every game.

Ultros. Don't tease the octopus kids! He is like the Jar Jar Binks of the FF universe.

And how can you hate on Toad? He flips off Mario and tells him to get out of his castle!

probably not my most hated one, but he's certainly much much worse than Vanille.

Flynn from Uncharted 2
Joker from ME

Link from Legend of Zelda.

There are several, actually. Let's see...

-Johnny Sasaki from the Metal Gear Solid series. He is one of the biggest stains on MGS4 for me.

-Ashley from Resident Evil 4. There is really nothing I can say that hasn't been said multiple times.

-Dante from the Devil May Cry series. A cardboard cutout of a cliché "cool" protagonist,  annoying, bland and one-dimensional.

-The whole cast of characters in Bayonetta (the original game), with emphasis on Bayonetta. Saturday morning cartoon personalities with saturday morning cartoon depth. Bayonetta herself was even more one-dimensional than Dante, something I thought couldn't be done.

-Ayumi Shinozaki from the Corpse Party series. She's an absolute cretin who throws her friends and herself in danger for no real reason other than the continuation of the plot and her stupid curiosity.

-Kratos from God of War. He became an utterly despicable and monstrous person after having somewhat understandable motivations in the original game. (SPOILER-SPOILER) The worst thing is the developers thought it would be a great idea to make him a martyr at the end of the story instead of committing to the "I became a monster" storyline. Cowards.

Sticks from Sonic Boom

Kratos

Ashley screaming "Leoooooon!" or Sheva wasting my green herbs.

Kratos. In the first game he almost had a personality, but than it became all hate.

He is not a cool badass (like maybe Dante, or even Kenpachi from Bleach), he is just an ass.