Aleister Crowley (born Edward Alexander Crowley; 12 October 1875 – 1 December 1947) was an English occultist, ceremonial magician, poet, painter, novelist, and mountaineer. He founded the religion of Thelema, identifying himself as the prophet entrusted with guiding humanity into the Æon of Horus in the early 20th century. A prolific writer, he published widely over the course of his life.

Thelema is a social or spiritual philosophy developed in the early 1900s by Aleister Crowley, an English writer, mystic, and ceremonial magician. The word thelema is the English transliteration of the Koine Greek noun θέλημα (pronounced [θélɛ:ma]), "will", from the verb θέλω (ethélō): "to will, wish, want or purpose". Crowley asserted or believed himself to be the prophet of a new age, the Æon of Horus, based upon a spiritual experience that he and his wife, Rose Edith, had in Egypt in 1904. By his account, a possibly non-corporeal or "praeterhuman" being that called itself Aiwass contacted him (through Rose) and subsequently dictated a text known as The Book of the Law or Liber AL vel Legis, which outlined the principles of Thelema.