| 143461 | December 21 | Birth | 1820 – William H. Osborn, American businessman (d. 1894) |
| 143462 | December 21 | Birth | 1830 – Bartolomé Masó, Cuban soldier and politician (d. 1907) |
| 143463 | December 21 | Birth | 1832 – John H. Ketcham, American general and politician (d. 1906) |
| 143464 | December 21 | Birth | 1840 – Namık Kemal, Turkish journalist, playwright, and activist (d. 1888) |
| 143465 | December 21 | Birth | 1843 – Thomas Bracken, Irish-New Zealand journalist, poet, and politician (d. 1898) |
| 143466 | December 21 | Birth | 1850 – Zdeněk Fibich, Czech composer and poet (d. 1900) |
| 143467 | December 21 | Birth | 1850 – William Wallace Lincoln, American son of Abraham Lincoln (d. 1862) |
| 143468 | December 21 | Birth | 1851 – Thomas Chipman McRae, American lawyer and politician, 26th Governor of Arkansas (d. 1929) |
| 143469 | December 21 | Birth | 1859 – Gustave Kahn, French poet and critic (d. 1936) |
| 143470 | December 21 | Birth | 1866 – Maud Gonne, English-Irish actress and activist (d. 1953) |
| 143471 | December 21 | Birth | 1868 – George W. Fuller, American engineer (d. 1934) |
| 143472 | December 21 | Birth | 1872 – Sidney Ainsworth, English-American actor (d. 1922) |
| 143473 | December 21 | Birth | 1872 – Lorenzo Perosi, Italian priest and composer (d. 1956) |
| 143474 | December 21 | Birth | 1872 – Albert Payson Terhune, American journalist and author (d. 1942) |
| 143475 | December 21 | Birth | 1872 – Trevor Kincaid, American scientist (d. 1970) |
| 143476 | December 21 | Birth | 1873 – Blagoje Bersa, Croatian composer and educator (d. 1934) |
| 143477 | December 21 | Birth | 1876 – Jack Lang, Australian politician, 23rd Premier of New South Wales (d. 1975) |
| 143478 | December 21 | Birth | 1877 – Jaan Sarv, Estonian mathematician and scholar (d. 1954) |
| 143479 | December 21 | Birth | 1878 – Jan Łukasiewicz, Polish-Irish mathematician and philosopher (d. 1956) |
| 143480 | December 21 | Birth | 1885 – Frank Patrick, Canadian ice hockey player and coach (d. 1960) |
| 143481 | December 21 | Birth | 1888 – Jean Bouin, French runner and rugby player (d. 1914) |
| 143482 | December 21 | Birth | 1889 – Sewall Wright, American geneticist and biologist (d. 1988) |
| 143483 | December 21 | Birth | 1890 – Hermann Joseph Muller, American geneticist and biologist, Nobel Prize laureate (d. 1967) |
| 143484 | December 21 | Birth | 1891 – John William McCormack, American lawyer and politician, 53rd Speaker of the United States House of Representatives (d. 1980) |
| 143485 | December 21 | Birth | 1892 – Amy Clarke, English poet, author, and academic (d. 1980) |
| 143486 | December 21 | Birth | 1892 – Walter Hagen, American golfer (d. 1969) |
| 143487 | December 21 | Birth | 1892 – Rebecca West, English journalist and author (d. 1983) |
| 143488 | December 21 | Birth | 1896 – Leroy Robertson, American composer and educator (d. 1971) |
| 143489 | December 21 | Birth | 1903 – Maria Balcerkiewiczówna, Polish-English actress (d. 1975) |
| 143490 | December 21 | Birth | 1905 – Anthony Powell, English author (d. 2000) |