- Sep 2 James Harrison Wilson, American topographic engineer and Major General (Union Army), born in Shawneetown, Illinois (d. 1925)
- Sep 7 Olive Oatman, American (as a teen captured and released by Native Americans), born in La Harpe, Illinois (d. 1903)
- Sep 14 Nikolai Bugaev, Russian mathematician, born in Georgia, Russian Empire (d. 1903)
- Sep 15 Leo van Gheluwe, Belgian composer, born in Wannegem-Lede, East Flanders (d. 1914)
- Sep 16 Pedro V van Alcantara, King of Portugal (1853-61), born in Lisbon (d. 1861)
- Sep 18 Aires de Ornelas e Vasconcelos, Portuguese Roman Catholic Archbishop of Goa, born in Funchal, Madeira, Portugal (d. 1880)
- Sep 19 Adolf Sonnenfeld, Polish violinist and composer, born in Wrocław, Poland (d. 1914)