The Cult of the Dragon was a cult within the Mechanicum during the 30th and early 31st Millennia, that lived on the Mechanicum's home world of Mars within the mysterious Noctis Labyrinth. The cult was regarded as a group of madmen in the desolate region of the Red Planet that they called home, a region that other members of the Mechanicum avoided at all costs. These individuals consisted of Tech-priests who long ago had tried to build their forges in the region that lies between the Valles Marineris and the Tharsis Uplands, but eventually abandoned them. However, the few that remained behind had formed the cult. The Cult of the Dragon worshipped the entity that was known to slumber deep beneath the Noctis Labyrinthus that some in the Imperium have come to believe might be the hibernating C'tan known as the Void Dragon. Others hold that this entity might in fact be the source of the Adeptus Mechanicus' belief in the Machine God.
Source
- Mechanicum (Novel) by Graham McNeill