Espada

The are the top-ranked Arrancar in Sōsuke Aizen's army of Hollow-Shinigami hybrids, are the most powerful Hollows under Aizen's command, and are the main rivals of the Gotei 13. Despite their late appearance into the plot, the Espada are often considered to be the primary antagonists of Bleach, particularly during the second half of the series, being responsible for much of the conflict that has transpired within the series' continuity.

Outline
The Espada are regarded as the most powerful Arrancar in existence. At any given time, the Espada has a nominal composition of ten members, all hand-picked and ranked by Aizen himself. Along with Aizen, Gin Ichimaru, and Kaname Tōsen, the Espada as a group possess comparable strength to Soul Society's Gotei 13 Shinigami captains.

At the time of the group's introduction, the Espada consists of nine males and one female. Each Espada member is chosen for their superior combat ability and then assigned a number from 1 to 10 (1 presumably being the strongest) that indicates their rank and relative power level, which is tattooed somewhere on their body. For instance, Grimmjow Jaegerjaquez's is located on the mid-back area and Coyote Starrk's is on the back of his left hand.

The Espada are given free control over the Números and may choose as many of them as they like to become their Fracción. 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. Aizen himself is confident enough of his Espada's abilities to send them out on potentially hazardous missions, such as gathering information in the real world, fighting Shinigami captains inside Las Noches and Karakura Town by themselves, and gathering the Vasto Lorde for his cause.

Being Aizen's most direct subordinates (not counting Gin Ichimaru and Kaname Tōsen), the Espada are privy to several of Aizen's plans and most intimate secrets, such as his goals of destroying Karakura Town and creating the King's Key and the location of the Hōgyoku within Las Noches. Aizen's respect for the Espada's abilities is reflected on his manner of addressing them, often referring to them as "my dear Espada" and sitting at the head of the same table with them, while discussing the events around Hueco Mundo. According to Dordonii, Aizen treats them as tools to do his bidding, but nonetheless, he wanted to take back his position as an Espada to once again be close to Aizen. In accordance with this, Aizen is not at all distressed over the deaths of the Espada and calmly congratulates the intruders in Las Noches for their victories against the Espada as he leaves for Karakura Town.

Their immense amount of power and leadership status among the Arrancar also grants each Espada the authority to exert command over Aizen's other forces within Las Noches: the Números, the Exequias, and their own Fracción. There seems to be a sort of hierarchy among the Espada; a higher-ranked member apparently can give orders to lower-ranked members. This is demonstrated when Aizen orders Ulquiorra Cifer to kidnap Orihime Inoue; the Arrancar led by Ulquiorra included Luppi (the then-sixth Espada), Yammy Rialgo (the tenth/zero), Grimmjow Jaegerjaquez, and Wonderweiss Margera (unassigned). Various missions usually involve one or more Espada operating together, with the most senior member exercising command over the others; typical, non-combat missions, such as searching for the Vasto Lorde and gathering pre-invasion data in the Human world, include a senior Espada and a lower-ranked one being sent out in pairs. While the lower-ranked members usually have little restraint in taking their own initiative (thus exceeding their orders), higher-ranked members usually stick to Aizen's commands, and are often the first to bail the others out of trouble, because in Nelliel Tu Oderschvank's own words, they wish to, "prevent the Espada from losing one of their own." However, Aizen's attitude toward the offending Espada members seem to be one of leniency, officially forgiving them (though not without severe sanctions) on the grounds that they are merely advancing his own wishes.

Aside from regularly appearing in Aizen's throne room and the debriefing room, the Espada are known to have their own quarters within Las Noches; those that have been seen appear to have been modified to suit the specific Espada's taste. Szayel Aporro Granz, for instance, possesses a large building that he refers to as his "palace," complete with a hidden, indestructible laboratory and a changing room; Zommari Leroux has been shown on one occasion to await orders inside a meditation room; Coyote Starrk's room is designed along the lines of a lounging chamber and Aaroniero Arruruerie's tower, accessed via a hanging bridge, effectively keeps out sunlight and contains nooks and crannies for hiding cushions and other implements whose purpose is to make his shape-shifting abilities more convincing.

As Aaroniero Arruruerie notes, all of the Espada, except for himself, were at least Adjuchas-class Menos before becoming Arrancar.

According to Ulquiorra, any Espada ranked 4th or higher are not allowed to release their Zanpakutō within Aizen's palace, as their Resurrección's released powers are powerful enough to destroy the majority of Las Noches.

Most recently, Yammy Rialgo stated that the Espada are not assigned numbers from 1 to 10, but rather, 0 to 9.

History
The creation of the Espada has long been one of Aizen's most important preoccupations. While it is not specified when the Espada were first brought together as a group, it is implied that the original Espada were already in existence sometime before Aizen's defection from the Soul Society and acquisition of the Hōgyoku. Since then, the composition of the Espada has changed, both in membership and position. As far as what kind of Arrancar have joined their ranks, only one member of the current Espada was a Gillian-class Menos, the others being at least Adjuchas, so Espada of the past have more prominently ascended from Gillians. Aizen has stated to Gin that his plans for the Espada include filling up its ranks with Vasto Lorde-class Arrancar, a process which he implies in the same statement as ongoing. Before his death, Aaroniero Arruruerie was the sole member of the current Espada who was also part of the first-generation Espada. Nelliel Tu was also the 3rd Espada for a time.

Former Espada
These are former Espada that did not become a part of the Privaron Espada because of certain circumstances.

Demotion
An Espada may be demoted from the Espada either when they lose strength or cease to be useful to Aizen, such as Grimmjow Jaegerjaquez after his left arm was cut off by Kaname Tōsen. In most cases, they will be demoted to the, who are former Espada that have officially lost their rank and are assigned a three-digit number.

Privaron Espada
The Privaron Espada 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.

Powers and Techniques

 * is a variant of the Gillian-exclusive ability Negación used to punish Arrancar subordinates by trapping them eternally in an alternate dimension. However, should the Caja Negación be used on an Espada, the Espada will eventually break out of the alternate dimension (usually within a few hours), due to their large amount of Reiatsu.


 * Like all other Hollows, they can use this blast technique. The Espada user fires a laser blast of great, concentrated destruction. While the color of most Ceros is red/crimson, several members of the Espada appear to have great color variations in their Cero; Ulquiorra's is green, Nnoitra's is golden yellow, and Nelliel's seems to be violet or pink (as she was using Cero Doble; it is unclear if her normal Cero is a different color). As he's the only Espada to have utilized its power on-screen, Grimmjow's liberal use of Gran Rey Cero, which emits a light-blue color, also counts, though his regular Cero is normally crimson.


 * is an Arrancar alternative to the Cero. The technique hardens the user's spiritual pressure and fires it like a bullet from their fist. Though somewhat weaker than a Cero blast, it moves about twenty times much faster than a Cero and can be fired at a much higher rate. This technique was first demonstrated by Wonderweiss Margera against Kisuke Urahara, and elaborated upon by Yammy during the same battle.


 * is a particular, very strong Cero. To perform this potent variation of the Cero, the Arrancar first draws blood from the Cero-generating appendage using his or her Zanpakutō, then charges the Cero while mixing the blood with it. The result is a Cero with a much greater attack power and speed, as well as a change of color unique to the Espada. This attack was first used by Grimmjow Jaegerjaquez in order to incite Ichigo into donning his Hollow mask. Grimmjow refers to it as, "the ultimate Cero". Grimmjow is, to date, the only Arrancar that has ever used Gran Rey Cero and Caja Negación on-screen.


 * is how Arrancar move to and from Hueco Mundo. Kaname Tōsen and Kisuke Urahara have also demonstrated the ability to use the technique. It literally tears open the dimensional fabric separating the worlds, revealing a tunnel of whirling, torrential energy that must be focused and solidified to create a discernible pathway.


 * refers to the hardened skin of the Arrancar, which is a result of their compressed spiritual power. While their skin is strong enough to block even released Zanpakutō bare-handed, it is by no means impenetrable. Stronger Arrancar have proportionally stronger skin. Nnoitra Jiruga claimed his Hierro is toughest amongst the Espada; being of higher rank than Nnoitra, Ulquiorra's Hierro appears to be much tougher.


 * is the Arrancar equivalent of the Shinigami ability to sense Spiritual Pressure. It functions similar to a sonar. Using Pesquisa requires most Espada to enter a meditative state; however, Nnoitra has a variation of this technique that involves placing his fingers to the ground to determine an opponent's approximate location as well as the amount of Spiritual Pressure an opponent has.


 * is the Arrancar equivalent of the Shinigami Flash Steps and the Quincy Hirenkyaku; it allows the user to travel at incredibly high speeds for short distances. Use of Sonído is punctuated by a brief static sound, in contrast to the "swish" sound used for Flash Steps. Zommari claims that his Sonído is the fastest amongst the Espada; Starrk and Ulquiorra appear to be faster, however, being the Primera and Cuarta, respectively.

Trivia

 * Most of the Espada's titles are the Spanish words for the ordinal of their rank (eg., Sexta means "Sixth" in Spanish). The only confirmed exceptions are Tia Harribel, who refers to herself as the "Tres Espada" rather than "Tercera," and Ulquiorra Cifer, who introduces himself as "Cuatro Espada" rather than "Cuarta."


 * Curiously, Nnoitra's and Aaroniero's ranks are in the masculine form, despite "Espada" being a feminine noun. Whether this is intentional or a mistake on the author's part is unknown.


 * Except for Luppi, all of the deceased Espada have died in their release forms, although Ulquiorra Cifer appeared to be slowly changing back just prior to his death.


 * Baraggan Luisenbarn, Ulquiorra Cifer, and Aaroniero Arruruerie are the only Espada whose Hollow mask remains are in the shape of some kind of helmet.


 * Despite being Grimmjow's replacement, it is unclear whether or not Luppi took his position as the Espada of Destruction. On the same note, it was never revealed if Nel was the Espada of Sacrifice or if Nnoitra was the Espada of Madness when he was the Octava.


 * The top five Espada all use a weapon while in their Resurrección.


 * While he's not an Espada, Wonderweiss Margera is classified with Espada-level spiritual energy by Soul Society.


 * Baraggan is the only Espada (and Arrancar), so far, that died by his own powers.


 * Harribel is the only Espada to be killed by Aizen himself.


 * All of the Espada, both current and former, have double letters in their names.


 * Luppi is the only Espada, current and former, not to have his full name revealed.