Xenu (), also called Xemu, is a figure in the Church of Scientology's secret "Advanced Technology", a sacred and esoteric teaching. According to the "Technology", Xenu was the extraterrestrial ruler of a "Galactic Confederacy" who brought billions of his people to Earth (then known as "Teegeeack") in DC-8-like spacecraft 75 million years ago, stacked them around volcanoes, and killed them with hydrogen bombs. Official Scientology scriptures hold that the thetans (immortal spirits) of these aliens adhere to humans, causing spiritual harm. These events are known within Scientology as "Incident II", and the traumatic memories associated with them as "The Wall of Fire" or "R6 implant". The narrative of Xenu is part of Scientologist teachings about extraterrestrial civilizations and alien interventions in earthly events, collectively described as "space opera" by L. Ron Hubbard. Hubbard detailed the story in Operating Thetan level III (OT III) in 1967, warning that the "R6 implant" (past trauma) was "calculated to kill (by pneumonia, etc.) anyone who attempts to solve it". The Church of Scientology normally only reveals the Xenu story to members who have completed a lengthy sequence of courses costing large amounts of money. The church avoids mention of Xenu in public statements and has gone to considerable effort to maintain the story's confidentiality, including legal action on the grounds of copyright and trade secrecy. Officials of the Church of Scientology widely deny or try to hide the Xenu story. Despite this, much material on Xenu has leaked to the public via court documents and copies of Hubbard's notes that have been distributed through the Internet. In commentary on the impact of the Xenu text, academic scholars have discussed and analyzed Hubbard's writings, their place within Scientology, and relationship to science fiction, UFO religions, Gnosticism, and creation myths. Summary The story of Xenu is covered in OT III, part of Scientology's secret "Advanced Technology" doctrines taught only to advanced members who have undergone many hours of auditing and reached the state of Clear followed by Operating Thetan levels 1 and 2. It is described in more detail in the accompanying confidential "Assists" lecture of October 3, 1968, and is dramatized in Revolt in the Stars (a screen-story – in the form of a novel – written by L. Ron Hubbard in 1977). Hubbard wrote that Xenu was the ruler of a Galactic Confederacy 75 million years ago, which consisted of 26 stars and 76