| 108841 | September 23 | Event | 1973 – Juan Perón returns to power in Argentina. |
| 108842 | September 23 | Event | 1980 – Bob Marley plays what would be his last concert in Pittsburgh. |
| 108843 | September 23 | Event | 1983 – Saint Kitts and Nevis joins the United Nations. |
| 108844 | September 23 | Event | 1983 – Gerrie Coetzee of South Africa becomes the first African boxing world heavyweight champion. |
| 108845 | September 23 | Event | 1983 – Gulf Air Flight 771 is destroyed by a bomb, killing all 117 people on board. |
| 108846 | September 23 | Event | 1986 – Jim Deshaies of the Houston Astros sets a major league record by striking out the first eight batters he faces in a game against the Los Angeles Dodgers. |
| 108847 | September 23 | Event | 1988 – José Canseco of the Oakland Athletics becomes the first member of the 40–40 club. |
| 108848 | September 23 | Event | 1992 – A large Provisional Irish Republican Army bomb destroys forensic laboratories in Belfast. |
| 108849 | September 23 | Event | 1999 – Celebrate Bisexuality Day was first observed in the United States. |
| 108850 | September 23 | Event | 1999 – NASA announces that it has lost contact with the Mars Climate Orbiter. |
| 108851 | September 23 | Event | 2002 – The first public version of the web browser Mozilla Firefox ("Phoenix 0.1") is released. |
| 108852 | September 23 | Event | 2004 – Over 3,000 people die in Haiti after Hurricane Jeanne produces massive flooding and mudslides. |
| 108853 | September 23 | Event | 2008 – Kauhajoki school shooting: Matti Saari kills ten people before committing suicide. |
| 108854 | September 23 | Event | 2010 – Convict Teresa Lewis became the first female inmate to die by lethal injection in the state of Virginia. |
| 108855 | September 23 | Event | 2015 – On Washington, D.C., Pope Francis canonized Father Junipero Serra as a saint. |
| 108856 | September 23 | Birth | 63 BC – Augustus, Roman emperor (d. 14) |
| 108857 | September 23 | Birth | 1158 – Geoffrey II, Duke of Brittany (d. 1186) |
| 108858 | September 23 | Birth | 1215 – Kublai Khan, Mongolian emperor (d. 1294) |
| 108859 | September 23 | Birth | 1434 – Yolande of Valois (d. 1478) |
| 108860 | September 23 | Birth | 1598 – Eleonore Gonzaga, Italian wife of Ferdinand II, Holy Roman Emperor (d. 1655) |
| 108861 | September 23 | Birth | 1642 – Giovanni Maria Bononcini, Italian violinist and composer (d. 1678) |
| 108862 | September 23 | Birth | 1647 – Joseph Dudley, American politician, Governor of the Province of Massachusetts Bay (d. 1720) |
| 108863 | September 23 | Birth | 1650 – Jeremy Collier, English bishop and theologian (d. 1726) |
| 108864 | September 23 | Birth | 1713 – Ferdinand VI of Spain (d. 1759) |
| 108865 | September 23 | Birth | 1740 – Empress Go-Sakuramachi of Japan (d. 1813) |
| 108866 | September 23 | Birth | 1759 – Marie Clotilde of France (d. 1802) |
| 108867 | September 23 | Birth | 1771 – Emperor Kōkaku of Japan (d. 1840) |
| 108868 | September 23 | Birth | 1778 – Mariano Moreno, Argentinian journalist, lawyer, and politician (d. 1811) |
| 108869 | September 23 | Birth | 1781 – Princess Juliane of Saxe-Coburg-Saalfeld (d. 1860) |
| 108870 | September 23 | Birth | 1791 – Johann Franz Encke, German astronomer and academic (d. 1865) |