Sans is a skeleton with red pupils, sharp teeth, and a single gold tooth. He wears a black jacket with fur over a red sweater, black shorts with golden stripes, and red shoes with yellow socks. He is often tired, grumpy, and annoyed, and sweats a lot. Despite his rude, sarcastic, and cocky exterior, he can be flirty and is described as needy, liking affection, kisses, and collars. He has teleportation and telekinesis powers, loves mustard, and enjoys telling knock-knock jokes.