The Bleach anime and manga feature an extensive cast of beings known as Hollows(虚 (ホロウ)Horō), the central antagonists of the series. These are malevolent, deceased souls of formerly ordinary humans in the Bleach universe. Much of the series focuses on the Arrancars(破面 (アランカル)Arankaru), more powerful variants of Hollows. The Arrancars make up the army of Sōsuke Aizen, the primary antagonist, and have a system of ranking based on strength. The most prominent Arrancars in the series are the ten most powerful Espadas(十刃 (エスパーダ)Esupāda) and their direct subordinates.