Nightmare is a skeleton monster. The character is calm and authoritative, He speaks politely. He only has one eye socket, which has a teal light in it. He has a black shirt with a blue tie and a black vest. On top he wears a black cloak. Nightmare's closest subordinate is called Killer, who often annoys him. Nightmare has tentacles that are made of negative energy. Nightmare feeds on negativity, so it enjoys other people's negative feelings. However, Nightmare does not kill unnecessarily.