I hate plenty. But, I will only name five
Rei from Highschool of the Dead for being a very shallow and annoying character, especially compared to Saeko
Dokuro from Bludgeoning Angel Dokuro-chan for being annoying and really mean spirited
Yuka fro Elfen Lied for being an incestuious freak, as well as annoying
Louise from Familiar of Zero for being a terrible tsundere
And Suguo from Sword Art Online for being a creepy child harassing sadist
Here's some I highly dislike in no order except the first one:
Shou from Fullmetal Alchemist (*bleh* too terrible for words)
Sasuke from Naruto Shippuden ONLY [NOT in the original Naruto!] (the overly-angsty emo)
Makoto from School Days (the wannabe-playboy)
Yuka from Elfen Lied (the incestuous jealous creep)
Nina from Code Geass (the table-rapist freak)