This is the story of those people, who have gone down in history as individuals, whose dark side, overshadowed not only their personality but also cast a dark shadow on society as a whole. This story about the worst serial killers in history, from around the world, throughout the centuries, shows how evil transcends all geographical and time barriers. Our list of the worst serial killers in history begins with Gilles de Rais. The story of the worst serial killers in history now passes to the new world: the United States of America, to be precise.