Ranks here because the scale of conquest and terror was immense, even though evidence and norms differ from modern dictatorships.
Best evidence
Genghis Khan created a vast empire through conquest campaigns that involved mass slaughter, terror tactics, city destruction, and forced submission across Eurasia.
Ranks at or near the top because the Holocaust, Nazi occupation policies, and World War II were tightly linked to his leadership and ideology.
Best evidence
Hitler's Nazi regime combined totalitarian rule, genocidal ideology, aggressive war, and industrialized mass murder, making him the clearest modern benchmark for catastrophic despotism.
Ranks extremely high because repression was sustained, institutionalized, and spread across a vast state for decades.
Best evidence
Stalin built a deeply repressive Soviet dictatorship marked by purges, forced collectivization, famine, mass deportations, gulag labor, and pervasive political terror.
Ranks in the top tier because policy decisions under Mao are associated with one of history's deadliest man-made famines.
Best evidence
Mao's rule produced immense human suffering through coercive campaigns, especially the Great Leap Forward famine and the Cultural Revolution's political violence.
Ranks high because the regime's radical social engineering killed a staggering share of Cambodia's population.
Best evidence
Pol Pot's Khmer Rouge regime attempted to remake Cambodia through forced evacuation, labor camps, executions, starvation, and genocide in an extraordinarily compressed period.
Ranks high because his personal colonial regime became a defining example of profit-driven despotic exploitation.
Best evidence
Leopold II personally controlled the Congo Free State, where rubber extraction was enforced through hostage-taking, mutilation, forced labor, and mass death.