42nd Division
- 42. Home Guard Infantry Division
- 42d Air Division
- 42nd (East Lancashire) Division
- 42nd Armoured Division (United Kingdom)
- 42nd Battalion (disambiguation)
- 42nd Brigade (disambiguation)
- 42nd Division (German Empire)
- 42nd Division (Imperial Japanese Army)
- 42nd Division (Spain)
- 42nd Group (disambiguation)
- 42nd Infantry Division (United States)
- 42nd Motor Rifle Division
- 42nd Regiment (disambiguation)
- 42nd Rifle Division (Soviet Union)
- 42nd Squadron (disambiguation)
- Austro-Hungarian Army
- New York Army National Guard