(Possibly) The Twenty (or so) Worst Things People Have Done to Each Other:
| Rank | Death Toll | Cause | Centuries |
| 1 | 66 million | Second World War | 20C |
| 2 | 40 million | Mao Zedong (mostly famine) | 20C |
| 40 million | Genghis Khan | 13C | |
| 4 | 27 million | British India (mostly famine) | 19C |
| 5 | 25 million | Fall of the Ming Dynasty | 17C |
| 6 | 20 million | Taiping Rebellion | 19C |
| 20 million | Joseph Stalin | 20C | |
| 8 | 18½ million | Mideast Slave Trade | 7C-19C |
| 9 | 17 million | Timur Lenk | 14C-15C |
| 10 | 16 million | Atlantic Slave Trade | 15C-19C |
| 11 | 15 million | First World War | 20C |
| 15 million | Conquest of the Americas | 15C-19C | |
| 13 | 13 million | An Lushan Revolt | 8C |
| 14 | 10 million | Xin Dynasty | 1C |
| 10 million | Congo Free State | 19C-20C | |
| 16 | 9 million | Russian Civil War | 20C |
| 17 | 7½ million | Thirty Years War | 17C |
| 7½ million | Fall of the Yuan Dynasty | 14C | |
| 19 | 7 million | Fall of Rome | 5C |
| 7 million | Chinese Civil Wars | 20C |
What other people say:
- "The destruction of the Indians of the Americas was, far and away, the most massive act of genocide in the history of the world." David E. Stannard, American Holocaust: the Conquest of the New World (1992) page x
- "The Mohammedan Conquest of India is probably the bloodiest story in history." Will Durant, The Story of Civilization: I - Our Oriental Heritage (1935) page 459. (seealso these)
- "Little did we guess that what has been called the century of the common man would witness as its outstanding feature more common men killing each other with greater facilities than any other five centuries together in the history of the world." Winston Churchill
