Satan, Dracula, Sauron, Lord Foul, Darth Vader. The motif of the Satanic Dark Lord is ever-present in science fiction and fantasy, a malign intelligence seeking to thwart the Chosen One. In the literature of the 1980s and 90s, the Dark Lord is always defeated. However, post-millennium, there are signs that he has finally begun to get the upper hand, as we witness his change from anti-hero to hero. In this enthralling study, prize-winning author A J Dalton considers how our understanding and characterisation of Satan has developed over time. From early depictions of Satan as a brutal dragon in the Bible, to the playfully seductive friend in the works of Chaucer and Marlowe, to the sympathetic and sensitive vampire of the modern-day, to the alien and unknowable artificial intelligence of tomorrow. This book provides a starting point for researchers, writers and fans of science fiction and fantasy interested in the development of one of the biggest tropes in speculative fiction.