Uglathu

The Uglathu, or worm hosts, seek the decay of both matter and spirit. Their ban means they can only possess humans of little morality, who are either dying or have just been killed. Once an Uglathu has a body, however, they begin their work; simply by being in proximity to humans, they eat away at their morality and integrity, making it harder for them to resist indulging in their vices. Victims exposed to Uglathu over a period of months will eventually degrade into sociopathy, being willing to do anything to gain what they desire.