Aleister Crowley

was a British occultist, writer, philosopher, and mystic.

He is best known today for his occult writings, especially The Book of the Law, the central sacred text of Thelema. Crowley was also an influential member in several occult organizations, including the Golden Dawn, the Argenteum Astrum, and Ordo Templi Orientis (O.T.O.).[2]
Other interests and accomplishments were wide-ranging—he was a chess player, mountain climber, poet, painter, astrologer, hedonist, drug experimenter, and social critic.

Crowley gained much notoriety during his lifetime, and was infamously dubbed "The Wickedest Man In the World."[4]

Born 12 October 1875
Royal Leamington Spa, Warwickshire, England
Died 1 December 1947 (aged 72)
Hastings, England

Crowley grew up in a staunch Brethren household and was only allowed to play with children whose families followed the same faith. His father was a fanatical preacher,

When he was a child, his constant rebellious behaviour displeased his mother to such an extent she would chastise him by calling him "The Beast" (from the Book of Revelation), an epithet that Crowley would later adopt for himself.

There have been about four men in my life that I could say I have loved... Call me a bugger if you like, but I don't feel the same way about women. One can always replace a woman in a few days.[21]

His friend and former Golden Dawn associate, Allan Bennett, introduced him to the ideas of Buddhism, while Samuel Liddell MacGregor Mathers, acting leader of the Golden Dawn organization, acted as his early mentor in western magic but would later become his enemy.

Mystical experience whilst on holiday in Egypt where he thought Horus an egyptian god wanted him to become the prophet of a new age of magic...

Thelema is the mystical cosmology Crowley announced in 1904 and expanded upon for the remainder of his life. The diversity of his writings illustrate his difficulty in classifying Thelema from any one vantage. It can be considered a form of religious traditionalism, humanistic positivism, and/or a meritocracy based upon libertarian elitism.
Chief among the precepts of Thelema is the sovereignty of Will: "Do what thou wilt shall be the whole of the Law." Crowley's idea of will, however, is not simply the individual's desires or wishes, but also incorporates a sense of the person's destiny or greater purpose: what he termed "True Will".
The second precept of Thelema is "Love is the law, love under will" — and Crowley's meaning of "Love" is as complex as that of "Will". It is frequently sexual: Crowley's system, like elements of the Golden Dawn before him, sees the dichotomy and tension between the male and female as fundamental to existence, and sexual "magic" and metaphor form a significant part of Thelemic ritual. However, Love is also discussed as the Union of Opposites, which Crowley thought was the key to enlightenment.