Arrancar Ranks

The arrancar under Aizen's command are arranged into various ranks based on their strength. Not all of the existing arrancar are under Aizen's command, mostly through lack of interest on Aizen's part.

The Espada (十刃（エスパーダ）, Esupāda?, Japanese for "ten blades," Spanish for "sword") are the top-ranked arrancar in Aizen's army. The Espada at the time of the group's introduction consists of nine males and one female.[5] Each Espada member is chosen for their superior combat ability and then assigned a number from 1 to 10 that indicates their rank and relative power level, which is tattooed somewhere on their body (Grimmjow's is on his lower back, for instance). The Espada are given control over the Números and are regarded as the strongest arrancar in existence. Similar to the power gap between captains and lieutenants in the Gotei 13, the strength of the Espada far surpasses that of the average Número. As Aaroniero Arruruerie notes, all of the Espada except him were at least adjuchas-class menos before becoming arrancar.

The Números (数字持ち（ヌメロス）, Numerosu?, Japanese for "number holders," and Spanish for "numbers") are the combat specialists. They are assigned a two digit number at birth from 11 to 99 to indicate their age (Número 11 is the oldest, Número 99 is the youngest). The basic Número uniform consists of a white-collared jacket and robes held with a black sash. However, the uniform is customizable, giving each Número a sense of individuality. The fighting ability of Números is thought to be superior to all other arrancar, except for the Espada (current and former).

The Fracción (従属官（フラシオン）, Furashion?, Japanese for "subordinate officers," Spanish for "fraction") are a subsection of the Números that directly serve a specific Espada. The number of Fracción for any given Espada varies: Stark and Nnoitra Jiruga would seem to have just one, while Szayel Aporro Granz has at least a dozen.

The Privaron Espada (十刃落ち（プリバロン・エスパーダ）, Puribaron Esupāda?, Japanese for "ten fallen blades," Spanish for "deprived") are former Espada who have officially lost their rank and are assigned a three-digit number. Being former Espada, they are far stronger than the normal Números. They reside in Tres Cifras, which translates literally from Spanish as "three digits". As mentioned by Dordonii, these former "naturally created" Espada were rendered obsolete after Aizen began artificially creating arrancar to meet his own standards.[6]

The Exequias (葬討部隊（エクセキアス）, Ekusekiasu?, Japanese for "funerary attacking force," Spanish for "funeral") are arrancar that are part of the execution division, apparently charged with termination of intruders and rebels. They are the equivalent of the Soul Society's Onmitsukidō