Hollow


 * Please note that this page will be edited further as the topic is expanded on in Bleach: Akujin Saga.

Hollow (虚, ホロウ, horō) are a race of creatures which are born from Human souls who, for various reasons, do not cross over to Soul Society after their death and stay in the Human World for too long. They are corrupt spirits with supernatural powers that devour the souls of both living and deceased Humans. Hollows are the principal antagonists at the beginning of the story and remain a primary threat beyond that point. Hollows settle in Hueco Mundo, but can cross over to the Human World and Soul Society.

Powers
Like Shinigami, Hollows have a multitude of combat skills and abilities, most of which are usually unique to specific Hollows. The more powerful Hollows, however, have access to a range similar techniques of greater power or use than their own unique skills. Hollows usually acquire energy to power their abilities by devouring souls, but smaller ones can also ingest energy from the atmosphere when in realms with high concentration of spiritual energy, such as Hueco Mundo.


 * Soul-Body Separation: Two middle class Hollow, Shrieker and Acidwire, have been shown using this ability, though presumably all Hollows have the ability. This technique allows a Hollow to forcibly extract a living spirit from his/her body. It is usually not used because Hollows tend to go after Pluses, who have no physical or living body to speak of. Acidwire used this on his younger sister, Orihime, so she could see and converse with him. Shrieker used it for more sinister means, causing the young boy Yūichi Shibata to be trapped within the body of a parakeet for three months while the Hollow chases him. The soul is still attached by the Chain of Fate and can be saved, but if it is broken (in Yūichi's case) then the soul can prevent the Encroachment so long as he/she is placed inside a soulless body or animal. It seems as though Shinigami have reverse engineered this ability, as shown with the Skull Symbol. It may or may not be possible that this ability could also extract a Shinigami from their Gigai, but this would obviously prove harmful to a Hollow.


 * Acidic Touch: Many Hollows, like Shrieker and Acidwire, have displayed this ability, although Rukia implies that all Hollows possess this power. When a Hollow grabs a Human with their hands, the spot where the person was grabbed is shown to get burned as if acid were poured onto it. This was shown when Orihime was grabbed in the leg, and on the wound on Chad's back. These wounds seem to allow the Hollow's reiatsu to seep into the person, causing great pain to the victim. The wounds can heal if given enough time though, and it is unknown if this ability works on Shinigami or other spiritually powerful beings.


 * is a highly powerful and relatively swift energy blast that can be fired from various body parts, such as mouth, tongue, hand or fingers. Only Menos, Arrancar, and Vizard have so far been shown to use Cero attacks, and it appears that stronger entities can use it more efficiently and forcefully. Cero also requires some time to be used effectively, so the enemy must be either not moving or busy with something else, or too badly wounded to even simply dodge it, with the exception of a few Cero techniques and users. Additionally, there exists quite a number of variations of Cero, which are usually unique to the Arrancar using it.


 * is how Hollows and Arrancar move to and from Hueco Mundo. Kaname Tōsen, Kisuke Urahara and recently Mayuri Kurotsuchi 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.


 * fields are used to rescue fellow Hollows. Only the Gillian-class Menos have shown the ability to use it. Espada have a special cube-shaped device called (Caja de Negación in the English dub) meant to simulate Negación fields, which are used to trap and punish their subordinates if necessary.


 * High-Speed Regeneration is the ability that allows a Hollow to heal most injuries very quickly, with the exception of the destruction of the head or vital organs. Only Menos-class Hollows have demonstrated this ability. Ulquiorra states that most Arrancar gave up Regeneration for far greater strength.


 * Hollow Shot is a blast that some Hollows have been seen using, it appears to be comprised of spirit particles.