Ordo Templi Orientis (O.T.O.) is an international religious and magical initiatory fraternity open to both women and men. The letters O.T.O. stand for Ordo Templi Orientis, the Order of Oriental Templars, or Order of the Temple of the East. O.T.O. is dedicated to the high purpose of securing the Liberty of the Individual and his or her advancement in Light, Wisdom, Understanding, Knowledge, and Power through Beauty, Courage, and Wit, on the Foundation of Universal Brotherhood.

O.T.O. was founded in Germany and England in the early part of the 20th century and was incorporated as a non-profit 501(c)(3) organization in California in 1979. It is currently organized in over 30 countries, with Grand Lodges in the United States, England, Croatia and Australia, and 155 official bodies worldwide. It still operates by the original charters, constitutions, documents, and principles established during its formative years. U.S. Grand Lodge is the governing body of O.T.O. in the United States. It is the most populous and active branch of O.T.O., with 62 local bodies as of 28 February 2022. 

Ordo Templi Orientis is the first of the traditional esoteric fraternities to accept The Book of the Law, received by Aleister Crowley in 1904 e.v.. This book proclaims a New Aeon in human thought, culture, and religion. The Aeon arises from a supreme injunction: the Law of Thelema, which is Do what thou wilt shall be the whole of the Law.

This Law is not to be interpreted as a license to indulge every passing whim, but rather as the mandate to discover one’s True Will and accomplish it; leaving others to do the same in their own unique ways. “Every man and every woman is a star.” The Law of Thelma can ultimately be fulfilled only through the individual efforts of each person. Nevertheless, many worthy aspirants to the Grear Work of Thelma have a genuine need for information, guidance, fellowship, or the opportunity to assist their fellow aspirants and serve humanity. Such aspirants will find welcome in

O.T.O., also includes the Ecclesia Gnostica Catholica (80C) or Gnostic Catholic Church, which is the ecclesiastical arm of the Order. Its central rite, which is public, is called Liber XV, or the Gnostic Mass.