10. Shou Tucker (Fullmetal Alchemist)
If you recognize this name, you know why Shou Tucker is hated. He is a man that is dedicated to his work and his nation. When pressed to make another speaking chimera, he does the only thing he knows how to. Bending his knees for his work, he sacrifices the only thing left that made him human, his daughter.
If that didn't automatically make you loath him, his further participation in the war effort would. The state finds out about his methods and supplies Shou with prisoners to expand his alchemy.
9. Makoto Itou (School Days)
Makoto Itou falls in love with a girl, and after dating quite a while he realizes that he does not get sexual satisfaction so he does it with his friend Sekai and makes her pregnant.
Makoto makes her life insane and although she kills him in the end but because of his death his girlfriend become insane and in the end his gf kills Sekai and then disappears with Makoto's dead body. School Days could force you to quit anime for a long time.
8. Light Yagami (Death Note)
From a person who wanted to criminals and crime to die, quickly rushes to become more and more evil. He let his father die, he was considering to sacrifice his sister to prevent the Death Note from being traded, he made his friend, also ex-girlfriend from college kill her self by setting the building on fire to make it look like an accident.
Obviously Light Yagami got all the hate from killing. Sexist, hypocrite, liar, manipulative, and arrogant. The guy has no limits; he'll step over anyone to achieve his goal, even to the point of killing his loved ones.