3rd Brigade may refer to:
Australia
3rd Army Tank Brigade (Australia) 3rd Brigade (Australia) 3rd Light Horse Brigade
Canada
3rd Canadian Infantry Brigade
Croatia
3rd Guards Brigade (Croatia)
France
3rd Mechanised Brigade (France)
India
British Indian Army in the First World War
3rd (Abbottabad) Brigade
3rd (Ambala) Cavalry Brigade
British Indian Army in the Second World War
3rd (Meerut) Cavalry Brigade
3rd Indian Infantry Brigade
3rd Indian Motor Brigade
Japan
IJA 3rd Cavalry Brigade
New Zealand
3rd (New Zealand Rifle) Brigade
Poland
3rd Brigade of the Polish Legions
3rd Polish Infantry Brigade
Polish 3rd Mountain Brigade
Serbia
LF 3rd Brigade
South Africa
3rd Infantry Brigade (South Africa)
Spain
3rd Mixed Brigade
Ukraine
3rd Tank Brigade (Ukraine) 3rd Separate Assault Brigade (Ukraine)
United Kingdom
3rd Cavalry Brigade (United Kingdom) 3 Commando Brigade 3rd Guards Brigade (United Kingdom) 3rd Infantry Brigade (United Kingdom) 3rd Mounted Brigade (United Kingdom) 3rd Parachute Brigade (United Kingdom) Artillery Brigades 3rd Brigade Royal Field Artillery III Brigade, Royal Horse Artillery III Brigade, Royal Horse Artillery (T.F.)
United States
3rd Brigade, 1st Infantry Division (United States) 3rd Brigade, 1st Cavalry Division (United States) 3rd Brigade, 7th Infantry Division (United States) 3rd Brigade Combat Team, 10th Mountain Division (United States) 3rd Brigade, 24th Infantry Division (United States) 3rd Brigade, 104th Division (United States) 3rd Marine Expeditionary Brigade (United States) 3rd Signal Brigade (United States) 3rd Sustainment Brigade (United States)