The men who attack Wolfwood in the Church. Under their masks, their mouths are sewn shut & they have screws in their eyes! Their jackets also resemble the Rodderick's...
Part Two begins with the (offscreen) gang rape and death by torture of a girl who's family had a long feud with another.
Leonof's Villainous Breakdown. It starts with him tearing his cheek, then his Fin Gore when defeated. plus his cases full of human viscera, Brad did not approve
Grey the Ninelives. In the anime he's indistinguishable from a robot, but in the manga, he cuts Descartes, the boomerang-throwing giant from Episode 1, in half with his own weapon. Then, when he faces Wolfwood, there's his "TRAITOR!!!" shriek. Unlike the anime version, he bleeds High-Pressure Blood & sheds tears! When his arms is severed, it crawls to the door release, so the main body can resume the battle. And it's mouth is...not right.
The opening to vol. 2 has Legato force a whole platoon of soldeirs into a tiny truck climbing in one after the other until they're all ground into pulp.
In Maximium Chapter 23, the giant Chinese-themed bandit attempts to rape a woman. "You will be my 13th wife", "The other 12 are all broken", and "You will join them in heaven now" are just a sampling of some of his creepier quotes. Good thing Meryl and Millie didn't approve.
The unnamed giant aiding Legato. It proves Not So Stoic & started flashing it's deformed mouth.
Raidei Rising massacre of the town he guarded combined with Tear Jerker.
Wolfwood blowing off all of Razlo's face near the end of their fight.
From Knives' "rebirth" scene to the atrocities performed on Tesla to quite a few of the Gung-Ho-Guns. The scene where Legato forced some thugs to march into a metal storage container. A large number of thugs. Far, far more than than the storage container could hold. Legato casually commented that the human body was in reality quite compact if it were just forced into the right shape. And he kept marching them into that container until blood leaked out the bottom.
Legato's Venom-esque tongue that he flashes when Razlo and Chapel first appear. It's a borderline Big Lipped Alligator Moment since it never pops up again, but the single image of it alone is incredibly freaky, especially since that's what's used to close the chapter out.
Legato in the anime was already a scary man. The manga however cranks it up even more. He's a cynical and depraved individual, all but outright stated to be a cannibal and by the end of the manga becomes a complete raving lunatic. Sprouting massive slasher smiles and laughing insanely all while making Vash's life absolute hell. What makes it noticeable is that unlike the anime, Manga Legato doesn't just come off as evil. He comes off as mentally sick where any possible good in him has been destroyed leaving only a deranged monster who finally forces Vash past the breaking point. Everyone else valued their lives or had some sort of morality. Legato was just too far gone in his own insanity to have any sort of morality whatsoever.
Legato Bluesummers. A personification of nihilism combined with the relentless drive of the Green Goblin, and telepathic powers that can make a person claw his heart out, shoot himself dead, or just turn them into puppets for him to speak through. His goal, his voice (in both Japanese and English), his theme (which sounds like a demonic stereo system), his ability to turn any potential kindness into cruelty—everything about this guy is absolutely terrifying. Only Legato can make eating sweets downright creepy.
Vash The Stampede himself. If you never meet him, if you're just simple townfolk who never gets to know the guy, you'd be terrified to death of a name known as The Humanoid Typhoon. Let's not forget that as good-natured as Vash can be, when he's absolutely enraged he becomes too much for anyone to handle. Don't believe me? Just ask Monev The Gale.