Most likely the magician author of the Book of Dzyan.  According to L. Sprague de Camp, this is a fictional book concocted by Helena Petrovna Blavatsky, founder of Theolophy, in her 'Secret Doctrine' (1888). She claimed that it was written by an Atlantian in the lost Senzar language.  Well, it is actually paraphrased without credit from an English translation of the ancient Sanskrit "Rig-Veda."

("The Haunter of the Dark")

See also: Book of Dzyan