The Horus Heresy

The Horus Heresy is a series of science fantasy novels set in the fictional Warhammer 40,000 setting of tabletop miniatures wargame company Games Workshop. Penned by several authors, the series takes place during the Horus Heresy, a fictional galaxy-spanning civil war occurring in the 31st millennium, 10,000 years before the main setting of Warhammer 40,000. The war is described as a major contributing factor to the game's dystopian environment.

The books are published in several media by the Black Library, a Games Workshop division, with the first title released in April 2006. The series currently consists of 65 published volumes; the concluding story, The End and the Death, was released in three volumes, with the concluding volume of the series, The End and the Death: Volume III, being released in January 2024.

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. 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. A sequel series, The Scouring, began publication in December 2025.