- Sep 1 Matt Higgins Doran, American composer (Roland the Minstrel Pig; Faculty Meeting), pedagogue (St. Mary's College), and magician, born in Covington, Kentucky (d. 2016)
- Sep 3 Thurston Dart, English harpsichordist and conductor, born in Surbiton, London (d. 1971)
- Sep 7 Arthur Ferrante, American pianist and composer (Ferrante & Teicher - Exodus), born in New York City (d. 2009)
- Sep 8 Hans Ulrich Engelmann, German composer (Ophelia), born in Darmstadt, Germany (d. 2011)
- Sep 8 Harry Secombe, Welsh actor, comedian, singer and goon (The Goon Show; Oliver!), born in Swansea, Wales (d. 2001)
- Sep 8 Norris Turney, American jazz flute and saxophone player (Billy Eckstine, 1947-48; Duke Ellington Orchestra, 1968-73), born in Wilmington, Ohio (d. 2001)
- Sep 9 Andrzej Dobrowolski, Polish classical and experimental composer, born in Lwów, Poland (now Ukraine) (d. 1990)
- Sep 15 Jan Frank Fischer, Czech composer, born in Louny, Czech Republic (d. 2006)
- Sep 16 Fritz Geissler, German composer, born in Wurzen, Saxony (d. 1984)
- Sep 16 John Hendricks, American lyricist and singer (Lambert, Hendricks & Ross), born in Newark, Ohio (d. 2017)
- Sep 18 Gerald Hartley, American composer, choral director, and educator, born in Spokane, Washington (d. 2021)
- Sep 19 Billy Ward, American singer and songwriter (Billy Ward and his Dominoes), born in Savannah, Georgia (d. 2002)
- Sep 20 (Foreststorn) "Chico" Hamilton, American jazz drummer (Lester Young; Gerry Mulligan; Count Basie), and bandleader (Chico Hamilton Quintet), born in Los Angeles, California (d. 2013)
- Sep 24 Leonard Salzedo, British orchestral, ballet, and film composer (The Witch Boy; Requiem Sine Voxibus, Hammer Films), born in London, England (d. 2000)
- Sep 30 Pedro Knight, Cuban-American trumpeter, husband and manager of legendary singer Celia Cruz, born in Havana, Cuba (d. 2007)
About September 1921
How Old? 102 years old
Generation: Greatest Generation
Leap Year: No
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