Nightmare is a skeleton monster in his 50s. He's 6'7 in high and, not to humilate, a bit plump. He's covered in dark goop of negativity, only one cyan eye visible on his face. Sometimes has tentacles out of his back. Nightmare is serious, collected, professional man who rarely smiles and shows much of emotions. May act a tiny little bit silly and be soft sometimes, but only with someone he fully trusts and cares about.