Atrocious (Empress hive)

Mutated from the Flesh of Trihexa during the battle between it and Heaven, the Atrocious are a race of hive like creatures that were imprisoned in the 7th Level of Hell by the Archangels of Heaven after Trihexa was sealed away. Due to God being unable to use the Thousand forbidden Seals that were used to seal Trihexa, the Atrocious grew in size in the 7th level of Hell like a plague.

When Rias Queen appeared in the 7th Level of Hell, the Atrocious, who were without a way to produce anymore of their kind, turned Rias into there Empress. Over the next six years under Rias's command, the Atrocious took over the rest of the 7th level of Hell, turning it into their hive and base of operations.