Cult of the Possessed
The Cult of the Possessed is a warband from Mordheim and is one of the few remaining examples in modern Warhammer Fantasy lore of a Chaos cult being devoted to a power other than Khorne, Slaanesh, Nurgle or Tzeentch. Arising after the destruction of Mordheim by a Wyrdstone meteorite, the Cult of the Possessed worships an entity known as the Shadowlord, which inhabits the great pit at Mordheim's heart. It would later be revealed that the Shadowlord is in fact Be'lakor, possessing the body of a powerful Chaos Champion.
The Cult revolves around a Magister; a Chaos-worshipping warlock who pulls double-duty as the warband's leader and its magic user. For heroes, a Cult may include up to 2 Possessed, daemon-occupied creatures that are the biggest bruisers in the band; they Cause Fear and start with a Mutation, and up to 2 Mutants, which are just human warriors with a mutation. For henchmen, the Cult can take any number of Brethren (basic worshippers), up to five Darksouls (former possession hosts who survived after their daemons were exorcised, but now believe they are daemons, which lets them auto-pass Leadership tests), and up to 3 Beastmen.