The Black Angels were a Chaos Space Marine warband active in the Eastern Fringe since at least the 37th Millennium. Believed to have been originally been a Loyalist AstartesChapter sworn to protect the very worlds they had come to terrorize, the Black Angels carved a bloody swath through the Eastern Fringe, enslaving planetary populations and forcing them to work to fuel the warband's efforts against the Imperium. However, the Black Angels suffered a major setback on the world of Aureth when more than half their forces, including their leader, Vorgath the Ruthless, were slain by the Avenging Fists Space Marine Chapter. Despite this major blow, after roughly 950.M41, rumors surfaced that the Black Angels were rebuilding under the leadership of a Daemon Prince known only as "The Horror that lurks beyond the sky" by the inhabitants of the Feral Worlds of its home sector. These rumors were later proven true when the Black Angels fought on behalf of the forces of Chaos in the Second Tyrest War.