Chaos Cultists on patrol
Mortals who serve the Chaos Gods come from many different walks of life. They may be dwellers of the Underhive who have succumbed to horrific diseases. They may be from a renegade Imperial Guard regiment that killed their loyalist commanders in a blood-fueled frenzy. They may be scholars who stumbled upon forbidden knowledge. They may be hedonistic aristocrats whose ambitions and pleasure-seeking have attracted the gaze of the prince of pleasure.
Whatever their origin, Chaos Cultists often seek to undermine the world they live on in numerous ways; by building cults dedicated to Chaos, encouraging sedition or summoning daemons. Or they may seek out the nearest warband of Chaos Space Marines, or any large force that resides in the Maelstrom or Eye of Terror. They are usually poorly armed with whatever weapons they could scavenge, though renegade Guardsmen tend to bring whatever tanks and equipment they already had with them, making them a formidable force. While a lucky few may earn the favor of the gods, the vast majority of cultists either die as meatshields, or are so horrendously abused by their masters that their minds snap.
Chaos Cultists are the main characters of the spinoff show Chaos Descends.