The OT levels are the upper part of "The Bridge to Total Freedom", which is the set of levels within Scientology. After having removed one's own "reactive mind" and thus attaining the state of "Clear", Scientologists may then go on to the OT levels. Scientology doctrine defines OT as the "highest state there is". Operating Thetan is represented by a symbol consisting of the letters OT with the T inside the O and each of the points of the T ending at the O's circumference.

An Operating Thetan (OT) is described within Scientology as a state of godliness, and Scientologists are taught they will have godlike control over "matter, energy, space and time" (known in Scientology jargon as MEST). Hubbard claimed that thetans were once tricked into following religions, which prevented them from using their own power to create and destroy universes.  The Church claims that an OT is not dependent on the physical universe, and Scientologists who have attained the highest Operating Thetan level claim that they have control over their lives and can "go exterior" from their bodies.