Bo Crowder's henchman Hestler Jones, is a convicted sex offender. He never does anything onscreen, but he's a very unsettling man.
Mags Bennett's ways of punishing her sons are simply terrifying.
The final scene in "Guy Walks into a Bar," in which Quarles snorts drugs and disrobes while talking incoherently. He walks naked into the bathroom, where Donovan is bound and gagged, suggesting Quarles has torture and sexual assault in mind.
Delroy beating up Ellen May.
Ellen May watching the doctor and her friend being brutally murdered while hiding under a desk.
Limehouse's slaughterhouse, where he chops up hog carcasses and the limbs of evil carpetbaggers.
In Slaughterhouse a desperate Quarles takes a mother and her two teenage sons hostages. After spending a few hours threatening to kill them if they do anything out of line, he forces the mother out of the car and and tells her eldest son to start driving without her. She runs after the car screaming. Later, Raylan can't even promise the woman her sons will be fine, since he knows Quarles's history and knows that, in all likelihood, they won't be.
The prospect of growing up with your own tombstone ready and waiting for you out in the backyard can be pretty terrifying.
Mason brutalizing Drew Thompson's widow after taking her captive in "Truth and Consequences". Had the marshals not shown up in time, it would have gotten even worse.
Jimmy on the receiving end of multiple snake bites in "Truth and Consequences". He and Colt snuck into Last Chance Salvation Church at night, only to discover that the St. Cyrs were using poisonous snakes to guard the tent.
The deaths of Sharon Edmunds and Arlo Givens are surprisingly horrifying for this show. The first gets shot in the neck and dies a slow, undignified death while the second gets messily beaten up and stabbed in the chest with scissors, only to collapse while making a lot of disturbing sounds.
When Boyd and Duffy visit Sammy Tonin in Detroit, Sammy's hands are covered in blood. Offscreen, a man is screaming in a nearby room, where one of Sammy's henchmen has taken a chainsaw. Apparently the Detroit Mafia uses cold blooded torture to punish its enemies.
Alan Tudyk as EliasMarcos. He made such a scary impression with his few minutes of screen time that some viewers actually thought he'd be more than a Filler Villain.
Daryl's villainous breakdown in "Weight". He brutally beats Wendy, leaving her stunned on the floor and shouting that he hates her. Then, he tearfully compels Kendall to forge a blood bond with him. Watching him slash his hand, slash a clearly frightened Kendall's hand, and forcefully clasp their hands together showed that Daryl is becoming dangerously unstable.
The scene offers a dose of fridge horror when viewers realize that Daryl could have any number of pathogens in his blood, given what we know of his sexual habits.
Daryl's beatdown of Mike isn't any easier to watch.
Ethan Picker's death. Boyd Crowder pulls out an ordinary carton of cigarettes, presses down on it, and then throws the carton to Picker. Seconds later, the carton, which is actually a bomb, explodes, obliterating Picker's chest and spraying blood all over the room. This is by far one of the most gruesome deaths in the entire series.
Mr. Yoon's Mexican drug cartel thinks decapitation is out of style. So they now remove the skin of their enemies.
Alberto Ruiz takes it up a further notch in "Restitution" when he describes in detail to Boyd how he will skin him.
When a handful of high-powered explosives reduce the Wiz to chunky salsa in "The Trash and the Snake", it's a combination of nightmare fuel and black humor.