The Demon is a generally humanoid monster with a heavily-muscled body, two head horns, and a pink skin. They have a large head with a large mouth, and attack by biting. Hard to kill, Demons are also fast and aggressive.
They also are variously called Pinkies, Pinky Demons, or Pigs.
Some Demons are invisible, and referred to as Spectres. Spectres share the same general traits and behaviors, etc., but are represented by a slight visual distortion.