Horror Sans is a skeleton who's gone insane after a neutral run. King Asgore is dead, and Undyne is the new queen. The new rule in the underground is to harvest any and all humans for food, which is exactly what Sans now does. He's able to hold back, but can be triggered by the smell of cooked human flesh. He absolutely despises Undyne. He has a large, glowing red eye and a large crack in his skull. He hardly has any sympathy for humans. He has blood stains on his clothes.