Graham Bruce Hancock (born 2 August 1950) is a British writer who promotes pseudoscientific theories about ancient civilizations and hypothetical lost lands. Hancock proposes that an advanced civilization with spiritual technology existed during the last Ice Age until it was destroyed following comet impacts around 12,000 years ago. He speculates that survivors of this cataclysm passed on their knowledge to primitive hunter-gatherers around the world, giving rise to all the earliest known civilizations (such as ancient Egypt, Sumeria, and Mesoamerica). Hancock's investigations of archaeological evidence, myths and historical documents superficially resemble investigative journalism, but they lack accuracy, consistency and impartiality. Relevant experts define his work as pseudoarchaeology and pseudohistory because it is biased towards preconceived conclusions by ignoring context, misrepresenting sources, cherry picking, and withholding critical counter-evidence. Hancock portrays himself as a culture hero who fights the 'dogmatism' of academics, presenting his work as more valid than professional archaeology. He has not submitted his writings for scholarly peer review and they have not been published in academic journals.

Born in Edinburgh, Hancock studied sociology at Durham University before working as a journalist, writing for a number of British newspapers and magazines. His first three books dealt with international development, including Lords of Poverty (1989), a well-received critique of corruption in the aid system. Beginning with The Sign and the Seal in 1992, he shifted focus to speculative accounts of human prehistory and ancient civilizations, on which he has written a dozen books, most notably Fingerprints of the Gods and Magicians of the Gods. His ideas have been the subject of several films, as well as the Netflix series Ancient Apocalypse (2022), and Hancock makes regular appearances on the podcast The Joe Rogan Experience to discuss them. He has also written two fantasy novels and in 2013 delivered a controversial TEDx talk promoting the use of the psychoactive drink ayahuasca.