501st
- 15th Cavalry Regiment
- 501 (disambiguation)
- 501st Combat Support Wing
- 501st Heavy Panzer Battalion
- 501st Infantry Regiment (United States)
- 501st Legion
- 501st Legion (Star Wars)
- 501st Military Intelligence Battalion (United States)
- 501st Military Intelligence Brigade (United States)
- 501st Squadron (disambiguation)
- 501st Sustainment Brigade (United States)
- 603rd Air Control Squadron
- Strike Witches
- Third Air Force