Khaos Brigade

The Khaos Brigade (禍の団（カオス・ブリゲード） Kaosu Burigēdo), also known as the Army of Disaster, is an organization in High School DxD. The Khaos Brigade consists of multiple races: Devils, Fallen Angels, Humans (who are descendants of legendary/mythological heroes), and a few (unfallen) Angels. They are the main antagonists of the light novels from the Birth of the Breast Dragon Emperor arc to the Legend of Oppai Dragon and his Lively Companions arc.

History
The Khaos Brigade was created by Ophis, the Dragon God of Infinity, with the sole purpose of removing the Great Red, the most powerful Dragon in existence known as the True Dragon, out of the Dimensional Gap.

Summary
The Khaos Brigade first appeared in Volume 4, introducing themselves to the world and attacking the leaders of the Christian religion's Three Factions. Shortly after that, the Khaos Brigade began to start many terrorist attacks, such as attacking the VIPs during Rias' Rating Game against Diodora, kidnapping the Youkai leader, Yasaka, and committing many other atrocious acts.

In Volume 11, the Hero Faction betrayed their leader Ophis after Cao Cao, the leader of the Hero Faction, sided with Hades, the God from the Realm of the Dead, and used Samael to steal most of her powers under the intention of creating another Ophis. This has resulted in the latter remaining in a presumed powerless state. However, Ophis released her powers in the form of snakes before Cao Cao came to steal her powers. As such, Ophis did not lose most of her powers.

As of Volume 12, the Khaos Brigade's two largest factions were greatly weakened by the loss of their leaders and various members. This has lead Azazel into speculating that the other factions of Khaos Brigade that have been lurking in the shadows will soon arise and take action. In Volume 14, Azazel reveals that there is someone who is trying to unify the remnants of the Old Satan Faction, Hero Faction, and Magician Faction.

Old Satan Faction
The Old Satan Faction (旧魔王派 KyūmaŌ-ha) is the largest faction of the Khaos Brigade consisting of Devils who are descendants of the original Satans: Beelzebub, Lucifer, Asmodeus, and Leviathan.

Hero Faction
The Hero Faction (英雄派 Eiyū-ha) is the second-largest faction of the Khaos Brigade led by Cao Cao, the descendant of Cao Cao from the Chinese novel Romance of the Three Kingdoms and the one who betrayed Ophis. It is a faction of the Khaos Brigade that is allied with Hades, the God from the Realm of the Dead, and it is also one of the most dangerous faction of the Khaos Brigade due to its members being Sacred Gear, Holy/Demon Sword, and Longinus wielders.

Magician Faction/Nilrem
Little is known about this faction, beyond the fact that it exists. It was first introduced in Volume 4 where the Magicians of the faction attacked the peace talks between the Three Factions. In Volume 14, it is revealed that these Magicians are those who were expelled by the Magician's Council.

Qlippoth
Qlippoth (クリフォトKurifoto) is an organization under Rizevim Livan Lucifer, which main purpose is to invade other worlds using the Evil Dragons. For that goal, they seek to defeat the Great Red which protects the Dimensional Gap.

Known members of Qlippoth includes:
 * Lilith, Ophis' spawn and Rizevim's personal bodyguard.
 * Euclid Lucifuge, brother of Grayfia Lucifuge.
 * Crom Cruach, the strongest Evil Dragon, also known as the Crescent Circle Dragon.
 * Grendel, an Evil Dragon, also known as the Crime Force Dragon.
 * Aži Dahāka, an Evil Dragon known as the Diabolism Thousand Dragon.

Vali Team
The Vali Team (ヴァーリチーム VarĪ Chīmu) is a special team of the Khaos Brigade led by Vali Lucifer, the descendant of Lucifer and the keeper of Albion, the White Dragon Emperor and the arch-rival of Ddraig, the Red Dragon Emperor. The Vali Team is not connected to any of the factions of the Khaos Brigade and it acts independently.