18th Battalion

18th Battalion may refer to:


 * 18th Battalion (Australia), a unit of the Australian Army 1915–1944
 * 2/18th Australian Infantry Battalion, a unit of the Australian Army 1940–1945
 * 18th Battalion (Western Ontario), CEF, a unit of the Canadian Expeditionary Force 1914–1917
 * 18th Logistics Battalion, a unit of the Belgian Army
 * 18th Battalion (New Zealand), a unit of the New Zealand Army 1939–1945