Espada
The Espadas (十刃（エスパーダ）, Esupāda?, Spanish and Portuguese for "sword," kanji translates as "ten blades") are the ten strongest Arrancars in Sōsuke Aizen's army and each of them represents an aspect of death. They are based at Las Noches (虚夜宮（ラス・ノーチェス）, Rasu Nōchesu?, Spanish for "The Nights," kanji translates as "Hollow Night Palace"), which was originally the Espada Barragan's domain, until Aizen took it over and remodeled it into his palace. The Espadas are ranked in order of their strength and have their respective numbers tattooed somewhere on their bodies as proof of their status. While it was originally thought the Espadas were ranked from 1 to 10, with 1 the strongest and 10 the weakest, they are according to Yammy ranked 0 through 9. Either way, one of the important rules Aizen set up was that Espadas of ranks 0 to 4 cannot use Resurreccións within the confines of Los Noches due to the immense spirit pressure. The Espadas are also allowed to personally choose any two-digit Arrancar, collectively known as the Números (数字持ち（ヌメロス）, Numerosu?, Spanish for "Numbers", Japanese translates as "Number Holders"), as their direct subordinate, referred to as their Fracción (従属官（フラシオン）, Furashion?, Spanish for "fraction," kanji translates as "Subordinate Official"; plural is Fracciones). Each Espada also possesses a Caja de Negación (反膜の匪（カハ・ネガシオン）, Kaha Negashion?, Spanish for "Negation Box"), a cube-like item meant to seal away any one Fracción as a punishment, and could possibly be held forever, but stronger Arrancars are able to escape from the Caja de Negación's subspace.
Read more about this topic: List Of Hollows In Bleach, Arrancar