43rd Regiment
- 43rd (Monmouthshire) Regiment of Foot
- 43rd Air Defense Artillery Regiment
- 43rd Battalion (disambiguation)
- 43rd Bomber Aviation Regiment
- 43rd Brigade (disambiguation)
- 43rd Division (disambiguation)
- 43rd Erinpura Regiment
- 43rd Georgia Volunteer Infantry
- 43rd Group (disambiguation)
- 43rd Illinois Volunteer Infantry Regiment
- 43rd Indiana Infantry Regiment
- 43rd Infantry Regiment (France)
- 43rd Infantry Regiment (United States)
- 43rd Mississippi Infantry
- 43rd New York Volunteer Infantry Regiment
- 43rd North Carolina Infantry
- 43rd Ohio Infantry
- 43rd Regiment Massachusetts Volunteer Infantry
- 43rd Royal Tank Regiment
- 43rd Squadron (disambiguation)
- 43rd United States Colored Infantry
- 43rd Wisconsin Volunteer Infantry Regiment
- Yugoslav Air Force