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.
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 just gets worse and worse from there.
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.
The Demon Lord Orgodemir from Dragon Quest VII definitely fits here. The hero's quest centers around traveling through time to Set Right What Once Went Wrong and unseal the rest of the world, as almost the entire planet descended into darkness thanks to the Demon Lord's warring against God. One has to play through the whole game to understand just how much this villain messed up the world. It's worth noting that he is the only villain in the entire franchise to be a direct parallel to Satan.
The Gittish Empire in Dragon Quest IX is notable for, as far as we're shown, being composed of nothing butComplete Monsters. Brutal, merciless soldiers who habitually conquer and subjugated the surrounding settlements, murdering anyone who resists, including women and children. And at one point, when one village surrendered, the Empire decided to slaughter them anyway. Special mention goes to their ruler, King Godwyn, who came to power in the first place by murdering his own father. If there's anyone who proves that Humans Are Bastards, it's these guys, to the point that it's incredibly likely that Zenus ultimately decided to try and exterminate humanity based on the Empire's atrocities alone. Oh, and did I mention that it was their depravity that made the Big Bad evil in the first place?
Pretty much the only shown Gittish people who are not complete monsters are Goresby Purrvis (an Affably EvilNoble Demon) and King Godfrey (the original ruler of the House of Gitt). Everyone else...not so much.
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, animal-like 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.
