| 21 September 19 BC | Roman Empire, Italy [births and deaths] | Virgil, Roman poet, dies in Brundisium, Italy (50), leaving his Aeneid unfinished. It is published posthumously. |
| 21 September 1327 | England [political events] | Edward II of Caernarvon, the former King Edward II of England 1307–27, is murdered in Berkeley Castle, Gloucestershire, in England (43). |
| 21 September 1558 | Holy Roman Empire, Spain [births and deaths] | Charles V, Holy Roman Emperor 1519–56, king of Spain as Charles I 1516–56, and archduke of Austria as Charles I 1519–21, dies in the monastery at San Jerónimo de Yuste, Spain (58). |
| 21 September 1676 | Papal States, Italy [Catholicism] | Benedetto Odescalchi is elected Pope Innocent XI following the death of Pope Clement X. |
| 21 September 1792 | France [administration] | The French National Convention convenes in Paris, replacing the Legislative Assembly. |
| 21 September 1832 | Scotland [births and deaths] | Walter Scott, Scottish novelist, poet, historian, and biographer who developed the historical novel, dies in Abbotsford, Roxburgh, Scotland (61). |
| 21 September 1866 | England [births and deaths] | H(erbert) G(eorge) Wells, English novelist, sociologist, and historian, who writes The Time Machine, The War of the Worlds, and The Invisible Man, born in Bromley, Kent, England (–1946). |
| 21 September 1893 | USA [motor vehicles] | Brothers Charles and Frank Duryea, who own a bicycle shop, test the first gasoline-powered car built in the USA. |
| 21 September 1898 | China [law and government] | Dowager Empress Zi Xi of China seizes power and revokes the reforms of Emperor Guangxu. |
| 21 September 1931 | United Kingdom [banking and finance] | Britain abandons the gold standard (the linking of the value of sterling to the Bank of England's gold reserves), signalling Britain's willingness to take economic decisions without regard to international finance. |
| 21 September 1957 | Norway [administration] | King Haakon VII of Norway dies and is succeeded by his son, Olaf V. |
| 21 September 1981 | Belize [decolonization] | Belize becomes an independent state within the Commonwealth. |
| 21 September 1993 | Russia [political events] | The Russian president Boris Yeltsin suspends the Russian parliament and calls elections; the Supreme Soviet defies this action and swears in Alexander Rutskoi as president. |
