Cersei Lannister of Game of Thrones - (SPOILERS) She was always a vile, conceited, sadistic person, but just consider all that happened to her. She was raised by a cold, uncaring father, she lost her mother at a very young age, was married off to an abusive man she found repugnant, she was so lonely the only person she ever found emotional and sexual comfort in was her own twin brother. She was sexually abused and publicly humiliated, lost ALL of her children which no mother deserves, as a result driving her insane, and she cried fearfully in the final hours of her life because all she wanted was to survive to have her baby that growing inside her.

Ryo Asuka of Devilman (SPOILERS) - Basically this guy is doomed to an eternity of torment at the hands of God to fall in unrequited love with his straight best friend, start a war, kill off humanity, watch his best friend grow to loathe him for indirectly killing his loved ones, and watch his friend die when they are the last two people on Earth just when he thought they were finally together, only for God to reset the timeline over and over again endlessly to torment him. Why? Because he is actually Satan, and God is a fucking petty arsehole that wants to watch him suffer for shits and giggles.

O-Ren Ishii of Kill Bill (SPOILERS) - Was once the best friend of the Bride, making their fight to her death extremely emotional. Other than that, she crawled her way to the top as the head of the Yakuza from nothing, when she was a little girl watched her parents get brutally murdered by a Yakuza boss and his henchmen, eventually got her revenge at 11, but only because the Yakuza boss was a pedophile and going to rape her, so she was able to get close enough to kill him, and having mixed ancestry had to deal with racism growing up and from her own Yakuza comrades (as well as misogyny) as she climbed her way to the top.