Kaaya from The Tower of Druaga: The Aegis of Uruk.
Oh, at the end of the last episode, she fucking betrays the entire group and Jil, where they both love each other but nooo~. Oh man, I fucking raged like crazy at the end of the episode, and I mean RAGE ATTACK, RAWRAWRARWRAWRAWR@#$%@#%%&#$%*#@$^@#$^%!!! - she pissed me off so much. (What is it with me a backstabbing anime girls that piss me off so much?) I mean, in the OP they're holding hands and shit, then she pulls an about face and goes with Neeba, Jil's fucking A excuse of a prick brother that he is.
She ain't getting my vote in the motemote, that's for sure. Can't wait until the second season starts.