Aaroniero Arruruerie (アーロニーロ・アルルエリ, Āronīro Arurueri) is an Arrancar in Sōsuke Aizen's army, and the noveno (9th) Espada.
He usually covers his face with an elongated white mask covered with eight holes while in the light. In place of a normal head, he has a large, glass cylindrical capsule filled with red liquid and two small, floating Hollow heads. The two heads are both tattooed with the number 9 and tend to talk in tandem when revealed, giving the effect of two people speaking in turn. The upper head speaks with a deep voice while the other speaks in a high-pitched, child-like voice. The heads appear to have a level of individuality. His outfit, like that of most Espada, is customized; he wears a dress garb that covers his entire body as opposed to the normal jacket and hakama. He also wears a frilly nobles' coat that acts as his replacement jacket and a single white gentleman's glove. The remains of his Hollow mask fragments are on both of his heads, the upper head having three-quarters of his head covered with the mask, and the lower head covering only half of it.