Hollow

Hollow and Bleach are Property of Kubo Tite, All Rights of the Author Reserved.

A vengeful class of spirit and the ultimate enemies of Shinigami, Hollow are spirits of the deceased who have lost their humanity due to loneliness, despair, and other negative emotions.

In time, they become powerful monsters due to the all-consuming void left in place of a heart. To fill this emptiness within, Hollow ravenously devour spirits of the recently deceased, of the living, and in some cases, even other Hollow. As Hollow consume more and more spirits, their power and intelligence continues to grow.

Appearance
While a Hollow can take nearly any shape or size, two traits always identify them: A bone mask covering the face and head, and a perfectly round hole through the torso and out the back, showing only blackness when viewing the sides from an angle.

As well, disregarding their sheer variety, the majority of Hollow have distinctly bestial forms - Ranging from hunched, lanky humanoids to completely animalistic. Lastly, they are easily recognized by their eyes: Glowing white circles in blank darkness.

Tendencies
Due to their unimaginable pain and hunger, Hollow are rarely able to maintain more than the faintest semblance of reasoning and sentience, outside of the most negative of emotions; i.e., anger, sorrow, the desire for vengeance, the grief of losing loved ones, etc., etc. Even should they maintain some of their original personality, the vast emptiness of their souls will eventually leave them either twisted into a true monster, or with no more intelligence than a rabid beast.

Abilities
Cero: An ability used by nearly all Menos of any level (See below), Cero (Spanish for "zero") are high-power energy blasts that are capable of great destruction.

Hierro: Common to Adjuchas-level Menos and higher, Hierro (Spanish for "iron") compresses the surface of the Hollow's spiritual body to increase defenses dramatically. Most Adjuchas use Hierro subconsciously, at all times.

Pesquisa: Decidedly rarer among even Adjuchas-class Menos, this technique allows them to quickly detect the spiritual energy of life forms.

Menos
Truth be told, Hollow who only prey on ghosts and humans cannot evolve further. When a Hollow's gnawing hunger for souls becomes so great that they begin to cannibalize other Hollow, they ascend to a greater level of power known as Menos (Spanish for "Minus"). Menos have three stages which have been vaguely touched upon in the game - Gillian, Adjuchas, and Vasto Lorde.

Gillian: The first and weakest class of Menos, Gillian all look identical because they have lost their sense of self. In the process of consuming so many souls, Gillian have become a sort of hive-mind that will obey any Menos stronger than themselves.

Only a handful of the innumerable Gillian in existence are able to become Adjuchas; this occurs when one Hollow identity within wrests control from the others, and begins to consume other Hollow at an even greater rate. This is signified, initially, by a unique mask appearing on an otherwise normal Gillian body.

As well, even though Gillian are relatively docile in comparison to other Hollow, making any move to attack one will lead to a retaliation by all others nearby. While slow-moving and largely ineffectual in attacking with their curiously-proportioned limbs, Gillian are surprisingly adept at firing Cero en masse without hitting each other.

Adjuchas: The next stage of Menos strength, Adjuchas have regained their individuality and are once again able to think for themselves. While Adjuchas bear a wide range of power and intelligence, they are uniformly stronger and smarter than any normal Gillian. Additionally, they are able to exert a degree of control over Gillian.

More often than not, the vastly smaller number of Adjuchas than Gillian can be found either hunting alone, in packs, or using numbers of Gillian to further their ends. Adjuchas are notorious for being combative and argumentiive infighters, especially to other Adjuchas who are their equals in strength.

Highly active, aggressive hunters, Adjuchas prey almost exclusively on other Hollow, as attacking singular humans or ghosts, one after another, could never sustain their forms. This is because, should an Adjuchas spend too much time without consuming souls, they will permanently regress to being Gillian.

Vasto Lorde: So rare that no Shinigami can lay claim to having seen one in person, Vasto Lorde are orders of magnitudes more powerful than the average Adjuchas, and their sheer level of strength and their fiercely independent spirit leave them able to weather centuries of inactivity without reverting to Adjuchas-level.

Reclusive and mysterious, Vasto Lorde are said to possess a strange ability to attract weaker Hollow into following them. These immeasurably strong Hollow reside in the deepest portions of Hueco Mundo, rarely if ever emerging even to feed.

While it is impossible to gauge the true power of any Vasto Lorde-level Menos - Due to their combat potency only being alluded to in rumors and hearsay - It can be said for sure that ten or more Vasto Lorde working in unison would be impossible for even the entirety of the Shinigami forces in any plane of existence to defeat without unimaginable casualties.

Arrancar
A unique class of Hollow, Arrancar have - Either by themselves or with the assistance of an outside force - Removed their masks to become yet more powerful. This gives them a much more humanoid form with only fragments of their mask and a Hollow hole to reference their origins, in addition to a Zanpakuto containing their natural form in a sealed state. Rather than Shikai and Bankai, Arrancar use a technique known as Resurreccíon to re-form a portion of their Hollow form and increase their power phenomenally. While Arrancar must return to human form eventually to not lose too much energy, it is possible for them to remain in their released form permanently: However, this is considered as absolute and drastic among themselves as amputating a limb.

Trivia

 * At least four characters - Ynot, Zev Raregroove, Hiyori Sarugaki, and Mashiro Kuna - Are mortals or Shinigami with some powers of Hollow. Ynot and Zev are also confirmed to possess Inner Hollow.
 * Most Hollow live in the world of Hueco Mundo when not in the Living World.