| 120331 | October 21 | Birth | 1328 – Hongwu Emperor of China (d. 1398) |
| 120332 | October 21 | Birth | 1449 – George Plantagenet, 1st Duke of Clarence, Irish-English son of Cecily Neville, Duchess of York (d. 1478) |
| 120333 | October 21 | Birth | 1527 – Louis I, Cardinal of Guise (d. 1578) |
| 120334 | October 21 | Birth | 1581 – Domenichino, Italian painter (d. 1641) |
| 120335 | October 21 | Birth | 1650 – Jean Bart, French admiral (d. 1702) |
| 120336 | October 21 | Birth | 1675 – Emperor Higashiyama of Japan (d. 1710) |
| 120337 | October 21 | Birth | 1687 – Nicolaus I Bernoulli, Swiss mathematician and theorist (d. 1759) |
| 120338 | October 21 | Birth | 1712 – James Steuart, Scottish economist and author (d. 1780) |
| 120339 | October 21 | Birth | 1725 – Franz Moritz von Lacy, Austrian field marshal (d. 1801) |
| 120340 | October 21 | Birth | 1757 – Pierre Augereau, French general (d. 1816) |
| 120341 | October 21 | Birth | 1762 – Herman Willem Daendels, Dutch general, lawyer, and politician, 36th Governor-General of the Dutch East Indies (d. 1818) |
| 120342 | October 21 | Birth | 1772 – Samuel Taylor Coleridge, English poet, philosopher, and critic (d. 1834) |
| 120343 | October 21 | Birth | 1775 – Giuseppe Baini, Italian priest, composer, and critic (d. 1844) |
| 120344 | October 21 | Birth | 1790 – Alphonse de Lamartine, French poet and politician, French Head of State (d. 1869) |
| 120345 | October 21 | Birth | 1811 – Filippo Colini, Italian actor and singer (d. 1863) |
| 120346 | October 21 | Birth | 1821 – Sims Reeves, English tenor and actor (d. 1900) |
| 120347 | October 21 | Birth | 1833 – Alfred Nobel, Swedish chemist and engineer, invented dynamite and founded the Nobel Prize (d. 1896) |
| 120348 | October 21 | Birth | 1845 – Will Carleton, American poet and journalist (d. 1912) |
| 120349 | October 21 | Birth | 1847 – Giuseppe Giacosa, Italian poet and playwright (d. 1906) |
| 120350 | October 21 | Birth | 1851 – George Ulyett, English cricketer and footballer (d. 1898) |
| 120351 | October 21 | Birth | 1877 – Oswald Avery, Canadian-American physician and microbiologist (d. 1955) |
| 120352 | October 21 | Birth | 1884 – Claire Waldoff, German singer and actress (d. 1957) |
| 120353 | October 21 | Birth | 1886 – Eugene Burton Ely, American soldier and pilot (d. 1911) |
| 120354 | October 21 | Birth | 1887 – Krishna Singh, Indian lawyer and politician, 1st Chief Minister of Bihar (d. 1961) |
| 120355 | October 21 | Birth | 1894 – Edogawa Ranpo, Japanese author and critic (d. 1965) |
| 120356 | October 21 | Birth | 1895 – Paavo Johansson, Finnish javelin thrower and decathlete (d. 1983) |
| 120357 | October 21 | Birth | 1895 – Edna Purviance, American actress (d. 1958) |
| 120358 | October 21 | Birth | 1898 – Eduard Pütsep, Estonian wrestler and actor (d. 1960) |
| 120359 | October 21 | Birth | 1907 – Nikos Engonopoulos, Greek painter and poet (d. 1985) |
| 120360 | October 21 | Birth | 1908 – Niyazi Berkes, Cypriot-English sociologist and academic (d. 1988) |