61st Regiment
- 61st Air Defense Artillery Regiment
- 61st Anti-aircraft Missiles Regiment (Romania)
- 61st Cavalry (India)
- 61st Cavalry Regiment (United States)
- 61st Georgia Volunteer Infantry
- 61st Illinois Volunteer Infantry Regiment
- 61st Indiana Infantry Regiment
- 61st Infantry Regiment (Finland)
- 61st Infantry Regiment (United States)
- 61st New York Volunteer Infantry
- 61st Ohio Infantry
- 61st Pennsylvania Infantry
- 61st Pioneers
- 61st Regiment Massachusetts Volunteer Infantry
- 61st Regiment of Foot (disambiguation)
- 61st Virginia Infantry
- British Army
- British Indian Army
- Finnish Army
- Indian Army
- Romanian Land Forces
- United States Army