Complete Monster/Dragon Quest

Dragon Quest games are renowned not only for firmly standing on the "idealistic" side of the Sliding Scale of Idealism Versus Cynicism, but also for having, in spite (or maybe because) of that, generally at least one utterly depraved, despicable villain per game, whether it's the Big Bad, The Dragon, or just another major player in the storyline's events.

Dragon Quest IV

 * Dragon Quest IV gives us Amon. Literally every single villainous act in the game, including Psaro's Start of Darkness, was orchestrated by him. He manipulates a group of humans to ruin Psaro's life and attack his girlfriend Rose, then manipulates Psaro into believing that Humans Are Bastards, setting him on his descent to evil. However, he was unsatisfied by how Psaro's relationship with Rose held his evil back and so arranges for her to be murdered, causing Psaro to be completely consumed by evil and turn into a mindless monster bent on destroying the world. The reason for all this? He wants the Secret of Evolution for himself so he can rule the world. What makes Amon especially monstrous is that he could've easily taken Psaro's place as the Big Bad from the getgo, sparing Psaro and Rose their torment and allowing them to live in peace. Instead, he ruins an innocent man's life and drives him to omnicidal madness, all For the Evulz.

Dragon Quest V

 * Bishop Ladja from Dragon Quest V, despite only being The Dragon, may very well be the most monstrous villain in the entire series, surpassing even Rhapthrone. Literally every time he appears, he commits an even more horrific atrocity than his last. His first scene alone has him brutally beating the hero and Harry (who are six years old at the time) to within an inch of their lives, laughing sadistically all the while, then, when the hero's father, Pankraz, arrives to save the day, he threatens to murder the hero if Pankraz tries to fight back against his enforcers. After the enforcers are done beating him, Ladja coldly finishes off the dying Pankraz with a giant fireball, then carts the hero and Harry off to a brutal slave labor camp for over ten years while making your young panther end up having to struggle for survival. And this is only his first appearance. He then follows up by turning the hero and his wife into stone so that they can watch him and Grandmaster Nimzo conquer the world. He's also at least somewhat successful at being The Starscream, killing off one person ahead of him (King Korol) in the chain of command for the power. Finally, he makes sure to wait until the main character reunites with his mother (after over 18 years apart) to kill said mother, just for maximum emotional impact.

Dragon Quest VI

 * Mortamor, the Big Bad of Dragon Quest VI, most definitely counts and was arguably tied with Ladja in terms of pure evil before Orgodimer and Rhapthorne came along. See, unlike the other DQ villains, Mortamor doesn't simply want to destroy/conquer the world. No, he wants to completely and utterly destroy the very concept of hope. To this end, he effectively turns his own world, which he rules, into a giant concentration camp where his subjects are routinely abused, manipulated, tortured, and slaughtered like animals. Those few who manage to resist his soul-crushing ways are instead shipped off to a special prison where they are starved, tortured, and ultimately executed hundreds at a time. Perhaps his worst act is manipulating an entire town to kill each other over a treasure chest he planted in an elderly woman's house. It's arguable which is worse: the act itself or the fact that the townspeople had been so thoroughly oppressed and broken that a single chest was all it took to drive every single one of them into a murderous frenzy.
 * Possibly the worst part is that Mortamor wasn't satisfied even after the slaughter. No, instead, he rewinds time to right before the massacre and starts the whole thing over again. The people of Greedmore, until the party's intervention, have been unknowingly trapped in an endless cycle of deceit, death, and rebirth for Goddess knows how long, all because Mortamor loves watching his subjects suffer.

Dragon Quest VII

 * The Demon Lord Orgodemir from Dragon Quest VII definitely fits here. Upon gaining power, Orgodemir entered a war with the Almighty and sent monsters to wipe out all life on the various islands of the world, succeeding in sealing away all but one of them. One of these islands, Buccanham, entered into an alliance with the Sea Dragon pirates in order to fight Orgodemir; in retaliation, he personally froze the pirates and their ship alive. Upon losing to the Almighty's Thanatos Gambit, Orgodemir tricks the heroes into reviving his spirit, disguised as the Almighty. He then starts his conquest anew by sealing away the islands that pose a threat and flooding the entire world with monsters before being defeated for good. It's worth noting that he is the only villain in the entire franchise to be a direct parallel to Satan.
 * Out of all of Orgodemir's minions that would do his bidding to satiate their personal desires, two stand out as particularly repulsive:
 * Cardinal Sin Tricks victims into letting them absorb their powers, he then traps them in a town known as Pilgrim's Perdition that is essentially a prison. The only one out is to murder others so they can take their souls. Those that resort to murder to save themselves are then made to fight each other to the death in an arena. And he doesn't actually plan on letting them legitimately winning their freedom. Instead, he murders those who win in the Colosseum with a fireball.
 * Togrus Maximus curses Buccanham so that any newborn baby would turn into a mindless monster on their first full moon, usually attacking their own parents before leaving.

Dragon Quest VIII

 * Rhapthorne from Dragon Quest VIII is one of the most repulsive villains in the series. While most main villains in the series are Card-Carrying Villain and/or Giant Space Flea From Nowhere, Rhapthorne is present from the beginning to the end, actively causing all the calamities in the game. His most heinous acts include turning the residents of the castle Trodian into immobile plant people, killing the kind old woman in cold blood (after forcing her to come out by holding her son hostage), and ordering the murder of an unborn child of the Godbird Empryea. Let's just say that his death was way too nice for what he did.

Dragon Quest IX

 * King Godwyn from Dragon Quest IX is a ruthless warmonger who wants to conquer the world, murdering anyone who resists, including children. And at one point, when one village surrendered, Godwyn has them slaughtered anyway. Not only that, but he . If there's anyone who proves that Humans Are Bastards, it's this guy, to the point that.

Dragon Quest XI

 * While Mordegon himself is the evil side of the Sage (indicating that he doesn't have an understanding of what is good), the Gloomnivore, a monster taking advantage of his reign has full moral agency. Enjoying feasting on despair, the Gloomnivore forces his victims to live out their worst memories so that it can keep them in a state of constant misery. One of these victims is the Hero's very own father, who lives out being murdered by King Carnelian. (He had been possessed by Mordegon, but he actually wasn't aware of that.) And yes, he plans to inflict the same fate on the hero.