The Great Beard's Bane

Overview
Lead by "Skin Peeler" Terry The Great Beard's Bane is the largest known cult in the empire, responsible for the deaths of millions of imperial citizens, and the complete fall of a city world. First sighted in early 1789 AF, the cult is now considered a major threat to the empire, and has been declared as rebels by the Emperor. Often referred to as the "Zombie Cultists", the GBB are often extremely disfigured, with sections of their flesh falling from their faces. This is due to the various rituals the cult partakes in, and the many flayings that occur within its members. The cult also practices the act of cannibalism, eating the corpses of those they 'cleanse'.

Induction Ritual
Very little is known about the cult, however a section of its introduction ritual is very well known. cultists at some point in the process are required to 'cleanse' a member of their family, and consume their corpse. This is posed as a test of their commitment to the cause, and it is noted that those who refuse to do this often go missing shortly after. Another known part of the ritual is to have sections of ritualistic armor to be fused with their bodies, and on some occasions, limbs are replaced with weaponry.

The Fall of Nova Gratian
In the year of 1975 AF, 186 years after its founding, The Great Beard's Bane rose up on the House Grafton colony of Nova Gratian, slaughtering it's populace, and claiming the planet as their own. The military garrison on the planet was quickly overwhelmed, as it found men within its ranks suddenly turn against them, and cultists began emerging from the subways and sewers, spewing into the streets and cutting down anyone in their path, with some stopping to carve flesh off the fallen and feasting on their corpses. Within just 3 hours all contact with the planet of lost, and a battle group under the command of High Inquisitor Astartes Kruger, who come into the planets orbit, and attempted to contact the cult. The only reply was a nearly inaudible transmission that was roughly interpenetrated as "Death to the Heretics! Fear the Great Beards! Fear their Bane!" The planet was declared as a quarantine zone and it's orbit is patrolled by the inquisition: a task normally left to the Imperial fleet. This strange act by the inquisition is still unexplained to this day, and nobody knows what is happening on the planets surface. All that is known is that warriors matching the description of the GBB were seen in the streets of Palavia, and that Grand Inquisitor has visited Nova Gratian on multiple occasions.