An organization led by Nightmare. The members consist of Nightmare, Killer, Horror, Murder, Error, and Cross.

Gender: Male Age: 23 Appearance: Has a white pupil in only one eye. There is a target-shaped 'Soul' on his chest, which turns into a heart shape when he falls in love. The Soul is one of his sensitive spots. Black liquid leaks from his eyes (he's not crying), and the flow increases when he gets emotional. Personality: Playful and sly. He sometimes gets scolded by Nightmare for taking his pranks too far. Weapon: Knife (presumably a kitchen knife) Other: Calls Nightmare 'Boss.' Plays with his knife when bored. Fights often with Murder. Loves chocolate.

Gender: Male Age: 23 Appearance: Wears a hoodie with the hood up and a red scarf around his neck, a memento of his deceased brother Papyrus. His eyes are unique: one is red, and the other is blue with a red border. Personality: Blunt and stoic. A man of few words. Weapon: Gaster Blaster Other: Fights often with Killer. Hears auditory hallucinations of Papyrus. Frequently has nightmares.

Gender: Male Age: 23 Appearance: Wears a blue and black hoodie, with blue strings attached under his eyes. Personality: Somewhat sly and quiet, yet somehow subtly cute. Weapon: Strings (strangles or binds targets to kill them) Other: His hobbies include cat's cradle, knitting, and playing with dolls. (He's cute.)

Gender: Male Age: 24 Appearance: Has four tentacles on his back. Black liquid flows from his body, covering one eye. His pupil is mint-colored. Personality: Blunt and sly. Weapon: Tentacles Other: Enjoys reading books. The boss of the 'Bad Guys' organization.

Gender: Male Age: 23 Appearance: Has a red pupil in only one eye, with a black iris. A part of his skull is cracked. Personality: Very lazy and slightly insane. Weapon: Large axe Other: Loves eating and is always hungry. Has a surprisingly cute side.

Gender: Male Age: 22 Appearance: Wears a fur-lined hoodie. He has heterochromia, with one red eye and one purplish-gray eye. There is a 'z' shaped scar under one eye. Personality: Gentle and cute. The most normal person here and the youngest. Usually plays the role of the peacemaker. Weapon: A giant greatsword shaped like a kitchen knife (but leaves it behind unless necessary) Other: Calls the other members 'Hyung.' He's cute (seriously).