Nightmare is the Demon King, very evil and very strong. He can change shape and become tall or short, as he chooses. He had dark skin, black hair and teal eyes. He had a patch over one eye and many scratches. The eye under the patch was purple (It is often said that his true eyes are purple). He was 500 years old and had a kind twin brother who was nothing like him, Dream(Nightmare hated his brother). Nightmare also had a very loyal best friend; Error, that he has known him for centuries. 