Papyrus (/pə.ˈpaɪ.ɹəs/, pa-PIE-rus), known as COOLSKELETON95 on UnderNet, is the younger brother of Sans and a major character in Undertale. He wants to capture a human so that he can become a member of the Royal Guard.

Papyrus is a tall, perhaps anatomically inaccurate skeleton with a skull shaped in a more straight and geometrical structure (in contrast to his brother's more rounded skull). His mouth is in a smile shape most of the time and his eyes are pupil-less, resembling vertical slits with his expressions being formed mostly by his skeletal pseudo-brows.

He wears a custom-made costume known as his "battle body", which is made up of a white torso piece with various golden trims (and embroidered with a symbol that very heavily resembles that of Starmen from the MOTHER series), a rough red scarf or cloth around his neck, red gloves (trimmed with gold), blue briefs with a golden belt, and long red boots.