81st Brigade
81st Brigade may refer to:
- 81st Mechanized Brigade (Romania), a unit of the Romanian Army
- 81st Mixed Brigade, a unit of the Spanish Republican Army
- 81st Brigade (United Kingdom), a formation of the British Army in the First World War
- 81st Armored Brigade Combat Team (United States), a unit of the United States Army
- 81st Airmobile Brigade (Ukraine), a unit of the Ukrainian Air Assault Forces