First, we have Aguilla Setme, master of memory alteration, who continues to tamper with the School Children's memories without much care of their welfare. Just look at how she crosses the Moral Event Horizon oh so many times to break Latooni. To make matters worse, she gleefully reveals that Aya and Mai are not Kenzo's true daughters as they believed - they just had their memories altered - and when Ryusei calls her out for it, her response is that, to her, human life has no value; they're just her research subjects.
Then we have Archibald Grims, a Psycho for Hire without a cause, whose objective is only to enjoy more bloodshed, especially if it's from innocents. He also gleefully forces Elzam to make a Sadistic Choice, whether it's to sacrifice his wife or commit mass murder on many people. His comeuppance from the Branstein brothers becomes very satisfying.
Archibald also has a predecessor in the form of Lubikka Hakinnen from SRW Gaiden. He doesn't even start out decent and the first thing we know about him chronologically is that he massacred Tytti's family right in front of her and swore to make her suffer and ENJOYED doing it. He almost became a Karma Houdini as he almost became a Herald of Elemental Lord, until Tytti reported his Complete Monster-ness, which caused him to flee and became Shutedonia's resident Psycho for Hire, doing jobs for its handsome pay and thrill on making people suffer. To hammer it down, he then killed Tytti's lover Ricardo RIGHT IN FRONT OF HER, all while having the crazed look of a would-be rapist.
Asakim Dowin from SRW Z also counts: he puts Setsuko through true hell just so she could awaken her power and kill him. What does he do? He kills her two friends in front of her, then beats her up in front of one of their corpses. Then he impersonates one of her friends...only to shoot her from the back. Then he brought Alternate Universe versions of her two friends and pit them off together. Unfortunately, Asakim is a Magnificent Bastard in that he mostly acts as a Complete Monster to Setsuko. In front of Rand, he tends to be less of a monster.
