Dictators responsible for massive crimes against humanity (over 20 million dead)
| Name | Country | Time in Power | Regime type | Notable Events | After... |
| Joseph Stalin | USSR | 1924-1953 | Communist | Revolutionary regime | died in office |
| Adolph Hitler | Germany | 1933-1945 | Fascist | World War II, Jewish Holocaust | committed suicide |
| Mao Tse-Tung | China | 1945-1976 | Communist | Revolutionary regime | died in office |
Dictators responsible for horrible atrocities (at least 1 million dead)
| Name | Country | Time in Power | Notable Events | Regime type | After... |
| King Leopold II | Belgium | 1865-1909 | Colonization of the Congo | Monarch | died in office |
| Kaiser Wilhelm II | Germany | 1888-1918 | World War I | Monarch | fled, died in exile |
| Czar Nicholas II | Russia | 1894-1917 | World War I | Monarch | overthrown, killed |
| Enver Pasha, member of triumvirate dictatorship | Turkey | 1913-1918 | Armenian genocide | Military | fled, died in rebellion |
| Vladimir Lenin | USSR | 1917-1924 | Russian Civil War | Communist | died in office |
| Emperor Hirohito | Japan | 1926-1989 | World War II | Monarch | died in office |
| Prime Minister Hirota Koki | 1936-1937 | Military | resigned, tried, executed | ||
| Prime Minister Tojo Hideki | 1941-1944 | Military | resigned, tried, executed | ||
| President Chiang Kai-shek | China / Taiwan | 1928-1949 | Chinese Civil War | Military | died in office |
| President Ho Chi Minh | North Vietnam | 1945-1969 | Vietnam War | Communist | died in office |
| President Kim Il Sung | North Korea | 1948-1994 | Korean War | Communist | died in office |
| President Yahya Khan | Pakistan | 1969-1971 | Indo-Pakistan War | Military | resigned, died |
| President Saddam Hussein | Iraq | 1969-2003 | Iran-Iraq War, Kurdish genocide | one party state | overthrown, tried, executed |
| Prime Minister Pol Pot | Cambodia | 1975-1979 | Cambodian genocide | Communist | overthrown, arrested, died awaiting trial |
| President Kim Jong Il | North Korea | 1994- | chronic famines | Communist | still in power |
Generally bad dictators (over 10,000 killed)
| President Kemal Ataturk | Turkey | 1920-1938 | one party state | died in office |
| Prime Minister Benito Mussolini | Italy | 1922-1943 | Fascist | overthrown, killed |
| Prime Minister Antonio de Salazar | Portugal | 1932-1968 | Fascist | resigned, died |
| Francisco Franco | Spain | 1939-1975 | Fascist | died in office |
| Prime Minister Ion Antonescu | Romania | 1940-1944 | Fascist | overthrown, tried, executed |
| Ante Pavelic | Croatia | 1941-1945 | Fascist | overthrown, died in exile |
| Gheorghe Gheorghiu | Romania | 1945-1965 | Communist | died in office |
| President Tito | Yugoslavia | 1945-1980 | Communist | died in office |
| President Yakubu Gowon | Nigeria | 1966-1976 | Military | overthrown, still living |
| President Suharto | Indonesia | 1967-1997 | Military | resigned, still living |
| President Idi Amin | Uganda | 1971-1980 | Military | overthrown, died in exile |
| President Mengistu Haile | Ethiopia | 1974-1991 | Communist | fled, lives in exile |
| President Le Duan | Vietnam | 1976-1986 | Communist | died in office |
| President Babrak Karmal | Afghanistan | 1979-1987 | Communist | resigned, died in exile |
| President Slobodan Milosevic | Yugoslavia | 1997-2000 | Fascist | resigned, arrested, died awaiting trial |
| President Omar al-Bashir | Sudan | 1989- | Military | Still in office |
