- Sep 7 Edward Grey, English viscount of Fallodon and Minister of Foreign Affairs, dies at 71
- Sep 8 Faisal I ibn Hussein ibn Ali, 1st king of Iraq/Syria, dies at 50
- Sep 16 George Gore, American baseball player, dies at 79
- Sep 17 Joseph De Piro, Maltese founder of the Missionary Society of St. Paul, dies at 55
- Sep 20 Annie Besant, English social reformer and supporter of Indian independence, dies at 85
- Sep 21 Eduard van Oort, Dutch ornithologist (Ornithology of Netherlands), dies at 56
- Sep 24 Mike Donlin, baseball player (b. 1878)
- Sep 24 Alice Muriel Williamson, British novelist (b. 1869)
- Sep 25 Paul Ehrenfest, Austria/Neth physicist, dies at 53
- Sep 25 Ring Lardner, American writer (b. 1885)
- Sep 29 Margaret Talmadge, dies