The shared universe was originally created in 1987 by Games Workshop, parent company of series publisher Black Library, as the campaign setting for the Warhammer 40,000 tabletop miniatures wargame and in 2006 Black Library began publishing The Horus Heresy series. The story focuses on the Emperor's 18 genetically engineered sons, the Primarchs, and the legions of genetically enhanced superhuman soldiers that they lead, the Legiones Astartes, which find themselves divided into loyalist and traitor factions as they struggle for religious hegemony. The Horus Heresy is presented as a major chapter of conflict in the Warhammer 40,000 lore: it is caused by a Chaos plot to foil the Imperium's leader and founder, the mysterious Emperor of Man, by fomenting rebellion and internecine warfare in the expanding Imperium of Man. The Horus Heresy is a dark, far future military space opera concerning an intergalactic civil war within the nascent Imperium of Man, and which constitutes a cornerstone event of the dystopian science fantasy Warhammer 40,000 universe. It is an established, definitive component of Games Workshop's Horus Heresy sub-brand, and authoritative source material for the entire Warhammer 40,000 shared universe and its continuing development. The series has developed into a distinct and successful product line for the Black Library titles have often appeared in bestseller lists, and overall the work has received critical approval despite reservations. The books are published in several media by the Black Library, a Games Workshop division, with the first title released in April 2006 as of February 2023 the series consists of 62 published volumes the concluding story, The End and the Death, will be released in two volumes, with the first released in February 2023.

The war is described as a major contributing factor to the game's dystopian environment. Penned by several authors, the series takes place during the Horus Heresy, a fictional galaxy-spanning civil war occurring 10,000 years before the far future of Warhammer 40,000. The Horus Heresy is an ongoing series of science fantasy set in the fictional Warhammer 40,000 setting of tabletop miniatures wargame company Games Workshop.

Graham mcneill fulgrim