Body thetan

A body thetan or BT is a concept in Scientology of a disembodied thetan (being) that is stuck in, on, or near a human body. All human bodies are said to be infested by BTs, or clusters of them.

Scientologists believe body thetans came about approximately 75 million years ago through a catastrophe brought on by a galactic dictator named Xenu, as described by L. Ron Hubbard in a confidential level in Scientology called OT III. High-level Scientologists are told that body thetans are responsible for physical and mental ailments, and are told to telepathically exorcize them using Scientology auditing processes.