1. Black Death
Death toll: 137 million (estimated 75 to 200 million)
Year: 1346–1353
Regardless of which death toll estimate you take into account, the Black Death remains one of the biggest epidemics in human history. Some experts claim 75 million, the others as much as 200 million dead in both Europe and Asia. When it finally subsided, Europe was in ruins. Between 40 and 60 percent of the entire population was dead. Entire villages and towns were completely emptied of their inhabitants. Large swaths of cultivated land were reclaimed by nature. The entire economic and political situation on the continent was uprooted and some of the consequences are still felt today, as the shortage of labor spurred technical innovations that reduced the need for it.