Secret Societies of the Middle Ages is a historical and antiquarian study by Thomas Keightley that examines reports, legends, and traditions about secret societies, mystery cults, and clandestine groups in medieval Europe. The book is not a modern academic analysis in the strict sense; instead, it reflects early 19th-century historical scholarship, combining documented history with folklore, legend, and speculative interpretation. Keightley attempts to trace the existence and influence of hidden or semi-secret organizations during the Middle Ages, including religious sects, mystical brotherhoods, and alleged conspiratorial groups.
