The Ordo Templi Orientis or O.T.O. is a magickal and fraternal organization devoted to the Law of Thelema. Founded by fringe Freemasons in 1902, it was designed to be a fusion of Western Mystery traditions and Indian Tantric practices. The infamous Aleister Crowley took over the organization in 1923, and held its leadership until his death in 1947. Today, the O.T.O. is an international organization with worldwide membership in the thousands.