Scientology founder L. Ron Hubbard explicitly compared his teachings to the science-fiction subgenre space opera. In his writings, wherein thetans were reincarnated periodically over quadrillions of years, retaining memories of prior lives, to which Hubbard attributed complex narratives about life throughout the universe. The most controversial of these myths is the story of Xenu, to whom Hubbard attributed responsibility for many of the world's problems.

Scientology is a set of beliefs and practices invented by the American author L. Ron Hubbard, and an associated movement. It is variously defined as a cult, a business, a religion, a scam, or a new religious movement. Hubbard initially developed a set of ideas that he called Dianetics, which he represented as a form of therapy. An organization that he established in 1950 to promote it went bankrupt, and Hubbard lost the rights to his book Dianetics in 1952. He then recharacterized his ideas as a religion, likely for tax purposes, and renamed them Scientology. By 1954, he had regained the rights to Dianetics and founded the Church of Scientology, which remains the largest organization promoting Scientology. There are practitioners independent of the Church, in what is referred to as the Free Zone. Estimates put the number of Scientologists at under 40,000 worldwide.