| 108271 | September 21 | Birth | 1987 – Ryan Guzman, American actor and dancer |
| 108272 | September 21 | Birth | 1987 – Murilo Maccari, Brazilian footballer |
| 108273 | September 21 | Birth | 1987 – Ashley Paris, American basketball player |
| 108274 | September 21 | Birth | 1987 – Courtney Paris, American basketball player |
| 108275 | September 21 | Birth | 1987 – Michał Pazdan, Polish footballer |
| 108276 | September 21 | Birth | 1988 – Doug Baldwin, American football player |
| 108277 | September 21 | Birth | 1988 – Bilawal Bhutto Zardari, Pakistani politician |
| 108278 | September 21 | Birth | 1989 – Jason Derulo, American singer-songwriter, dancer, and actor |
| 108279 | September 21 | Birth | 1989 – Sandor Earl, Australian rugby player |
| 108280 | September 21 | Birth | 1989 – Jef Gaitan, Filipino actress and singer |
| 108281 | September 21 | Birth | 1989 – Emma Watkins, Australian singer and actress (The Wiggles) |
| 108282 | September 21 | Birth | 1990 – Al-Farouq Aminu, American basketball player |
| 108283 | September 21 | Birth | 1990 – Danny Batth, English footballer |
| 108284 | September 21 | Birth | 1990 – Ivan Dorschner, American-Filipino model and actor |
| 108285 | September 21 | Birth | 1990 – Allison Scagliotti, American actress |
| 108286 | September 21 | Birth | 1990 – Christian Serratos, American actress |
| 108287 | September 21 | Birth | 1991 – Anastassia Kovalenko, Estonian motorcycle racer |
| 108288 | September 21 | Birth | 1992 – Rodrigo Godínez, Mexican footballer |
| 108289 | September 21 | Birth | 1993 – Kwon Mina, South Korean singer and actress (AOA) |
| 108290 | September 21 | Birth | 1993 – Derik Osede, Spanish footballer |
| 108291 | September 21 | Birth | 1994 – Fumi Nikaidō, Japanese model and actress |
| 108292 | September 21 | Birth | 1994 – Ben Proud, English swimmer |
| 108293 | September 21 | Death | 19 BC – Virgil, Roman poet (b. 70 BC) |
| 108294 | September 21 | Death | 454 – Flavius Aetius, Roman general and politician (b. 396) |
| 108295 | September 21 | Death | 687 – Pope Conon (b. 630) |
| 108296 | September 21 | Death | 1217 – Lembitu, Estonian soldier |
| 108297 | September 21 | Death | 1217 – Caupo of Turaida |
| 108298 | September 21 | Death | 1235 – Andrew II of Hungary (b. 1175) |
| 108299 | September 21 | Death | 1327 – Edward II of England (b. 1284) |
| 108300 | September 21 | Death | 1397 – Richard FitzAlan, 11th Earl of Arundel, English admiral (b. 1346) |