Espada

The are the top-ranked arrancar in Aizen's recently-acquired army of hollow-shinigami hybrids, the most powerful hollows under Aizen's command, and the main rivals of the Gotei 13 and the Ryoka. 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 transpired within the show's 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 branded by Aizen himself. Along with Aizen, Gin Ichimaru, and Kaname Tōsen, the Espada as a group possess comparable strength and numbers to Soul Society's Gotei 13 and its thirteen 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 being the strongest) 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 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.

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, the location of the Orb of Distortion within Las Noches, and the name and illusory abilities of his zanpakutō. 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 does not think of them as mere underlings, and he wanted to take back his position as an Espada to once again be close to Aizen.

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. Unlike their Gotei 13 counterparts, 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 to kidnap Orihime Inoue; the arrancar led by Ulquiorra included Luppi (the sixth), Yammy (the tenth), Grimmjow Jeagerjaques, 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 Neliel Tu Odershvank'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, Stark'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 him were at least adjuchas-class menos before becoming arrancar.

According to Ulquiorra, the top four Espada are not allowed to release within Aizen's palace, as their resurreccions are powerful enough to destroy the majority of Las Noches.

History
The creation of the Espada has long been one of Aizen's most important preoccupation. 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 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 Adjuchas or higher, 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. Nel Tu was also the 3rd Espada for a time, along with her Fracción. It is possible that Grimmjow is one of the oldest Espadas since most of his Fracción are the oldest Numeros.

Former Espada
These are the Espada that have either died or left Las Noches and did not become part of the Privaron Espada.

Demotion
An Espada may be demoted from the Espada, such as Grimmjow Jeagerjaques when 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 (Spanish: 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. It may be that the Privaron Espada numbers are simply their old number turned into a three digit one. (Ex. Dordonii was the 103rd and he may have been the 3rd in the original Espada)

Devices and Techniques

 * Caja Negación is 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.


 * Cero: 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 famous members of the Espada appear to have great color variations in their Cero; Ulquiorra's is green, Nnoitra's is golden yellow, and Neliel'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 it's power on-screen, Grimmjow's liberal use of Gran Ray 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.


 * Gran Rey Cero: (王虚の閃光, グラン・レイ・セロ; Spanish for "grand king zero") 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 zanpakuto, 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 Jeagerjaques in order to incite Kurosaki into donning his hollow mask. Grimmjow refers to it as "the ultimate cero", as Gran Rey Cero is apparently a result of shinigami-hollow hybridization (both arrancar blood and a zanpakuto is required to use this technique). Grimmjow is, to date, the only arrancar that has ever used Gran Rey Cero and Caja Negacion 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 claims 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; Stark and Ulquiorra appear to be faster, however, being the Primera and Cuarta, respectively.


 * is a black Cero, which can presumably only be used by Espada in their released state. The result of being used in their released state is a much more powerful Cero, possibly rivaling Gran Ray Cero, and has been referred to as a "fully-powered Cero." However, it is too early to tell for sure if it can be accessed by all Espada and not just Ulquiorra, because only Gran Rey Cero, coupled with any Espada above Cuatro releasing their power, are forbidden under Las Noches. Obviously, Cero Oscuro should be forbidden as well, since an Espada ranked below 4th (perhaps Nnoitra) should be able to use Cero Oscura after his/her ressureccion under Las Noches. Ulquiorra also referred to it as "[his] cero," depicting a sense of ownership.

Trivia

 * Interestingly enough, Yammy introduces himself as "Espada Diez, Yammy!" (Espada 10, Yammy! in Spanish) when he fights Captain Hitsugaya during their mission to kidnap Orihime Inoue, whereas all other Espada introduce themself with XXth numbers. This may be a mistake on Tite Kubo's part or Yammy is just a special case.
 * Following the pattern set by the other Espada, Yammy's title should be "Décima Espada" (literally "10th Sword" in Spanish).
 * "Privaron Espada" literally means "they deprived the swords" in Spanish. "They" could refer to Aizen and the current Espada.
 * The Espada's titles are all the Spanish words for the ordinal of their rank (eg., Sexta means "sixth" in Spanish).
 * Curiously, all of the (revealed) titles are in the feminine form. Nnoitra and Aaroniero are exceptions; their titles are in the masculine form.
 * The tattoos indicating the Espadas' position doesn't seem to be permanent. Example: During the flashback, Nnoitra had his postion as the 8th Espada tattooed on his tongue. However, when he revealed his current position as the 5th Espada to Ichigo, the number 5 has replaced the previous number 8. This might be possible as Aizen is constantly artificially creating Arrancars to meet higher standards, and this will be convenient for him to demote current Espadas if those tattoos can be erased. It might be possible for the Privaron Espadas to not reveal their tattoos as their previous rank to their enemies because they might be already erased. Nel is an exception to still have her tattoo despite not being an Espada as she was not demoted, rather ambused by Nnoitra and Szayel.
 * Barragan, Zommari and Szayel Aporro are the only Espada who have not revealed their tattoos.
 * So far, the Espada two numbers down from each other have had similar ressurecion tactics or abilities. Whilst this may not be Kubo's intention or if this will continue, from what has transpired so far, it appears to be the case. I.E: Szayel (8) and Zommari (7) were both Espada who had abilities that crippled people in their release states. Grimmjow (6) and Nnoitra (5) are two Espada that are mostly combat driven Espada that don't gain many abilities, but they excel in superior combat and speed.
 * Wonderweiss may not be an Espada by rank but Soul Society registers him as an Espada or of equal power to.
 * Barragan, Halibel, Zommari, Szayel, and Aaroniero are the only Espada with apparently no Hollow hole.
 * Ironically, Stark and Shunsui are the most alike, since almost every Espada has something negative about them, where as Stark and Shunsui are exactly alike.
 * Luppi is most likely a promoted numeros or even a Privaron Espada. He seemed to enjoy gloating about his new status even to Grimmjow. What's more, his release was certainly strong but not exactly a current leveled Espada release, i.e: a gross bodily metamorphisis where the Espada literally becomes the creature rather than just adding extra limbs or appendages. Also, Luppi is instantly annialated by Grimmjow when his arm is restored. Both were heavilly patched up so their status in power should have been equal.
 * So far, Zommari is the only Espada that has not taken the form of an animal in their released state. Szayel seemed as though he had this in common, but upon further inspection it was found his powers resemble that of a helminth or parasitic worm.