September 23 is the 266th day of the year (267th in leap years). There are 99 days remaining.
- 1713: Ferdinand VI (King of Spain)
- 1889: Walter Lippmann (journalist)
- 1920: Mickey Rooney (actor)
- 1926: John Coltrane (saxophonist, composer)
- 1949: Bruce Springsteen (singer)
- 1959: Jason Alexander (actor)
- 1959: Lita Ford (singer, guitarist)
- 1959: Elizabeth Peña (actress)
- 1835: Vincenzo Bellini, aged 33, Italian composer (Norma)
- 1939: Sigmund Freud, psychiatrist
- 1973: Pablo Neruda, poet
- 1846: Discovery of Neptune by German astronomer Johann Gottfried Galle
- An equinox usually occurs on this date.