Rocketeer, poet, and polyamorous proto-feminist, Jack Parsons (1914-1952) is one of the earliest and most legendary followers of Aleister Crowley (1875–1947) and his religion Thelema in America. A precocious only child and avid sci-fi reader, Parsons made vital contributions to the American space programme, and was briefly regarded by Crowley as a potential successor. However, Parsons’ romantic side, keen imagination, and tendency to be seduced by literary fiction was a source of friction between the two men. Parsons drew freely on gothic horror as well as pulp and sci-fi literature in articulating his personal magical universe. In 1946, he undertook the ‘Babalon Working’: a series of magical operations aimed at manifesting the goddess Babalon on earth as a sort of Thelemic messiah. This paper will explore the importance of literature for Parsons’ magical worldview and experimentation, focusing on three key works: Crowley’s Moonchild, Jack Williamson’s Darker Than You Think, and M.R. James’ short story »Count Magnus«.