Anubis Maryoku (Revolution War)

Anubis Maryoku was the youngest son of the main branch of the Maryoku Clan and the most powerful of the Lemures and Commander of the Yōkai Goei under his friend Sōsuke Aizen, Anubis was charmed with experimenting on forbidden Kidō spells and he was officially charged with imprisonment while unofficially he was experimented on by Mayuri Kurotsuchi through the usage of the Fracta Obscurus, after being fully experimented on with a number of other people the created Lemures were transformed into Hollows to cover up the research with Anubis being one of the few taking on a Vasto Lorde-like Hollow form.

Anubis remained in Hollow form until he came into contact with Sōsuke Aizen who had just removed the Hōgyoku from the Rukia Kuchiki, close contact between Anubis and the Hōgyoku caused Fracta Obscurus to override the Hollowfication command set down by Mayuri Kurotsuchi back when he covered up his experiments, returning back to a human form the Lemures led Aizen to each of the Hollowfied Lemures which were also set free by the Hōgyoku. The Lemures, united as a squad of their own under Anubis, announcing that they would be Aizen's version of the Royal Guard and use their powers to fulfill his desires.

Trivia

 * In Egyptian Myth, Anubis is the Egyptian God of death and funerals.
 * Maryoku is a Japanese word meaning "Magic Power".