Wonderweiss is a childish arrancar. He has a thin, childlike body. Short, light blond hair, bright purple eyes, freckles and two visible sharp teeth. His hollow mask consists of a three-point tiara on his head. Aizen stripped away all forms of rationality, memory retention, speech, and intelligence from him, leaving Wonderweiss to be very childlike. Due to his modifications, he cannot properly speak. He can act hostile when in possible danger, or defensive, out of instinct.