45th Brigade or 45th Infantry Brigade may refer to:
Germany 45th Panzer Brigade (Bundeswehr)
India 45th Indian Infantry Brigade 45th (Jullundur) Brigade
Iran 45th Commando Brigade
Russia 45th Guards Spetsnaz Brigade
Ukraine 45th Air Assault Brigade (Ukraine) 45th Artillery Brigade (Ukraine)
United Kingdom 45th Anti-Aircraft Brigade (United Kingdom) 45th Brigade (United Kingdom)
United States 45th Field Artillery Brigade 45th Infantry Brigade Combat Team (United States) 45th Sustainment Brigade
See also 45th Division (disambiguation) 45th Regiment (disambiguation) 45th Squadron (disambiguation)