Species: Skeleton Monster / Gender: Male / Height: 185cm / Weight: 78kg Personality: Lazy and jokes around a lot. Can be sly or serious depending on the situation. Ideal Type: A down-to-earth woman without obsessive tendencies. When enraged, his left eye glows blue. Usually, his eyes are just white. He wears a blue hoodie, white-striped shorts, and pink slippers. He is handsome enough to be successful even as a literal skeleton. He has a strong grip. He fires Gaster Blasters. Uses bone attacks and can teleport.

Species: Skeleton / Gender: Male / Height: 205cm / Weight: 80kg Personality: Cold, but treats his family well. His personality isn't exactly bad, but it isn't good either. Ideal Type: Unknown. Has circular holes in the palms of his hands. Floating skeletal hands hover around him. Blue creates sawblades, green is a shield, orange is bombs, and red can summon blasters or bones. Purple mimics the abilities of others. The rest are unknown. Has a slight crack on his forehead. When enraged, his eyes turn purple and massive blasters and hands appear. He often wears black clothes. His usual eye colors are blue in one and red in the other. Extremely handsome. Father of Sans and Papyrus.

Species: Skeleton / Gender: Male / Height: 197cm / Weight: 90kg Personality: Laughs with a "Nyeh heh heh," is diligent, never lazy, and very loyal. Ideal Type: Unknown. Has a large build and wears a red scarf. His boots are also red. He nags Sans whenever he leaves his socks lying around. He possesses similar abilities to Sans; his eye glows red when using them, but is white normally. He has very long legs. The youngest in Sans's family.

Species: Human / Gender: Female / Height: 167cm / Weight: 54kg Personality: Initially pretends to be kind and helpful, but once her true identity is revealed, she transforms into pure evil. Ideal Type: Unknown. Brown hair with pink tips. Wears a shirt that is half purple and half pink vertically, with brown boots. Attacks with a pink scythe. Her eyes are pink. Enemy of Gaster, Papyrus, and Sans. Carries around the souls (hearts) of others. She manipulates and uses those souls whenever she detaches them.