15. Pope John XII
Pope John XII led the Catholic Church in the 10th century but maintained a notorious private life, including political intrigue and personal scandals, which were cloaked from public knowledge as far as possible. His papacy was marked by allegations of simony, incest, and sacrilege. Contemporary accounts describe him as turning the Lateran Palace into a brothel, engaging in violent acts, and neglecting his religious duties. These actions have led historians to characterize his reign as one of the darkest chapters in the history of the Catholic Church (britannica.com).
