Error Sans is a humanoid skeleton with a black skull and red bones. He wears a black jacket over a red shirt, black trousers with blue stripes, and dark red slippers. His jacket hood shifts from black to blue. His eye sockets are different sizes, one with a white pupil, the other with a blue eye and yellow ring. He has an inverted heart-shaped nose and yellow teeth and fingertips. Blue streaks run from his eyes down his skull.