EVOLUTION OF HOLLOW
Menos Classifications
Though most Hollows are simply transformed Human souls, a sub-group of Hollows known as Menos Grande (大虚 (メノスグランデ), menosu gurande; Spanish for "Less Big" or "Big Minus", Japanese for "Great Hollow"), or simply Menos (メノス, menosu; Spanish for "Minus" or "Less"), exist. Menos are conglomerations of hundreds of normal Hollows, resulting in a single composite entity of far greater strength than any normal Hollow.[21]
Menos are created when the void within an ordinary Hollow's heart becomes so substantial Human souls are incapable of sustaining it, at which point it begins devouring fellow Hollows. These cannibal Hollows are attracted to one another, and a mass inter-devouring follows, resulting in a Gillian. Following this transformation, the Gillian can evolve twice more, first into an Adjuchas and finally into a Vasto Lorde, provided certain conditions are met.[22] Menos evolution is not only contingent upon the Menos eating other Hollows, but also upon the Menos' ability to avoid being eaten. If another Hollow succeeds in devouring even a part of their body, evolution becomes impossible for the one who was wounded this way.[23] Menos-class Hollows are considered so dangerous Soul Society sends only highly trained Shinigami teams to handle them.[21] These incursions seem to be rare, however, as Menos rarely leave Hueco Mundo unless attracted by large sources of spiritual power or encouraged to by other forces. There are three categories of Menos: Gillian, Adjuchas, and Vasto Lorde
Gillian (最下大虚 (ギリアン), girian; Japanese for "Lowest Great Hollow") are the first and weakest of all Menos. In Human terms, they would be considered foot soldiers. There are many of them, and they all look alike. In Soul Society, they are the "Menos" who are generally referred to in textbooks. Gillians are huge, but they are slow and have beast-like intellect. Any captain-level Shinigami can destroy them with ease.[25] Up to the point when Rukia Kuchiki meets Ichigo Kurosaki, she had only seen them in such textbooks, despite having been a Shinigami for many years. Gillians commonly attack in a group, and one is powerful enough to be a challenge for a Lieutenant of the Gotei 13. Gillians typically arrive in the Human World through the use of spatial distortions called Kūmon (空門, lit. "Air
Adjuchas (中級大虚 (アジューカス), ajūkasu; Japanese for "Intermediate Great Hollow") are the second classification of Menos. They are smaller than Gillians and far fewer in number. They are much smarter and stronger than Gillians, and are often the ones who lead Gillians into battle.[29] Adjuchas are commonly solitary creatures, rarely joining into groups. They are powerful enough to challenge a captain of the Gotei 13.
Vasto Lorde (最上大虚 (ヴァストローデ), vasuto rōde; Japanese for "Highest Great Hollow") are the third classification of Menos and the highest level of evolution. They are extremely rare in number, and it is said that their entire number within Hueco Mundo can be counted with the fingers on one's hands. The combat capabilities of a Vasto Lorde are said to be above those of the captains of the Gotei 13.[29]
other classifications
Arrancar
An Arrancar is a Hollow which has removed its mask, thus gaining Shinigami-like powers.
Visored
he Visored is a group of Shinigami who have been banished from Soul Society after obtaining Hollow powers.[46]
Fullbringer
A Fullbringer is a spiritually aware human who inherited remnants of Hollow powers leftover from an attack on the Fullbringer's parents, prior to birth.[47]