18th Regiment or 18th Infantry Regiment may refer to:
18th Infantry Regiment (Imperial Japanese Army) 18th Regiment "Edolo", a unit of the Italian Army 18 (UKSF) Signal Regiment, a unit of the British Army 18th Royal Hussars, a unit of the British Army 18th Infantry (British Indian Army), a unit of the British Indian Army 18th Infantry Regiment (United States), a unit of the United States Army 18th Marine Regiment (United States), a unit of the United States Marine Corps Royal Irish Regiment (1684–1922) was formerly the 18th Regiment of Foot
American Civil War regiments
Confederate (Southern) Army regiments 18th Regiment Alabama Infantry 18th (Carroll's) Arkansas Infantry Regiment 18th (Marmaduke's) Arkansas Infantry Regiment 18th Georgia Volunteer Infantry 18th North Carolina Infantry 18th Virginia Cavalry 18th Virginia Infantry
Union (Northern) Army regiments 18th U.S. Colored Infantry 18th Connecticut Infantry Regiment 18th Illinois Volunteer Infantry Regiment 18th Iowa Volunteer Infantry Regiment 18th Regiment Indiana Infantry 18th Regiment Massachusetts Volunteer Infantry 18th Michigan Volunteer Infantry Regiment 18th Missouri Volunteer Infantry 18th New Hampshire Volunteer Infantry 18th New York Volunteer Infantry 18th Kansas Militia Infantry Regiment 18th Regiment Kentucky Volunteer Infantry 18th Ohio Infantry 18th Vermont Volunteer Infantry Regiment 18th Wisconsin Volunteer Infantry Regiment
See also XVIII Corps (disambiguation) 18th Division (disambiguation) 18th Brigade (disambiguation) 18th Battalion (disambiguation) 18 Squadron (disambiguation)