Rudolf Freiherr von Sebottendorf was the alias of Adam Alfred Rudolf Glauer (November 9, 1875 – May 8, 1945), who also occasionally used another alias, Erwin Torre. He was an important figure in the activities of the Thule Society, a post-World War I German political organization that was a precursor of the Nazi Party. He was a practitioner of sufi meditation and astrology.

Glauer was born in Hoyerswerda, Saxony, Germany, the son of an engine driver from Dresden. He used the alias Sebottendorf because he claimed that he had been adopted by the Sebottendorf family and had a claim to the title of count. After a career as a merchant seaman, Glauer settled in Turkey in 1901 and became the supervisor of a large estate there.

Glauer was deeply influenced by Sufi mysticism, other Eastern philosophies, and in particular, the writings of Madame Blavatsky. He used Blavatsky's The Secret Doctrine to launch his own recreation of ancient Germanic myth, positing a coming historical moment in which he theorized that the Aryan race would be restored to prior glories by the appearance of a race of Supermen. Glauer eventually became the prime mover behind the Thule Society, which was one of the most important precursors of the Nazi Party, although the Nazi Party itself, once it had become ascendant, obliterated the Thule Society.

The Thule Society, which espoused ideas of extreme nationalism, race mysticism, virulent anti-Semitism, and the occult, was formed shortly after the end of World War I in Munich by Glauer. It attracted about 250 ardent followers in Munich and about 1500 in greater Bavaria. Members of the Thule Society included Rudolf Hess, Dietrich Eckart, and Alfred Rosenberg. Thule agents infiltrated armed formations of the Communist Party in Munich and plotted to destroy the party, hatching plans to kidnap the party's leader, Kurt Eisner, and launching an attack against Munich's Communist government on April 30, 1919. The Thule Society also started its own newspaper, Müncher Beobachter, in 1918, and eventually approached the organizer Anton Drexler to develop links between the Society and various extreme right workers' organizations in Munich.

Drexler was instrumental in merging the Thule Society with a workers' party that he was involved with. The merged organization became known as the München Deutsche Arbeiterpartei (DAP). It was the DAP that Adolf Hitler was introduced to in 1919. By April 1, 1920, the DAP had been reconstituted as the Nazi Party, and Glauer, who was accused of negligence in allegedly allowing the names of several key Thule Society members to fall into the hands of the Communists, resulting in the execution of seven members after the attack on the Munich government in April 1919, had fled Germany for Switzerland and then Turkey. He returned to Germany in January 1933, but fled again in 1934. He was an agent of the German military in Istanbul during the period 1942–1945 (while apparently also working as a double agent for the British military). Glauer allegedly committed suicide by jumping into the Bosphorus on May 8, 1945.

• Note regarding personal names: Freiherr is a title, usually translated Baron, not a first or middle name.