Sōsuke Aizen
As an albino hollow ostracized by other dark-colored hollows, Ulquiorra is revealed in side stories to have come into being as a Vasto Lorde ages ago before the balance of life and death was established where hollows manifested from the chaotic influx rather than from human souls. As an Espada member who represents the aspect of death of Emptiness, Ulquiorra is emotionless with an inability to comprehend the meaning of "heart" and supports his firm belief that what his eye cannot see does not exist. Bent on completing tasks set to him by Sōsuke Aizen, Ulquiorra has no qualms about attacking his own allies if they impede his intent and deems anyone he finds not to be of particular interest to be "trash," and therefore expendable. The remainder of Ulquiorra's hollow mask, partially destroyed before his conversion, forms a broken helmet with a curved horn and covers the left half of his head. His hollow hole has moved since his first appearance; when first introduced it is at the base of his neck, but in later appearances, it is centered just below his collarbone.