18th Regiment

• 18 (UKSF) Signal Regiment
• 18 Squadron (disambiguation)
• 18th Alpini Regiment
• 18th Arkansas Infantry Regiment (Carroll's)
• 18th Arkansas Infantry Regiment (Marmaduke's)
• 18th Battalion (disambiguation)
• 18th Brigade (disambiguation)
• 18th Connecticut Infantry Regiment
• 18th Division (disambiguation)
• 18th Georgia Volunteer Infantry
• 18th Illinois Volunteer Infantry Regiment
• 18th Infantry (British Indian Army)
• 18th Infantry Regiment (Imperial Japanese Army)
• 18th Infantry Regiment (United States)
• 18th Iowa Volunteer Infantry Regiment
• 18th Kansas Militia Infantry Regiment
• 18th Marine Regiment (United States)
• 18th Michigan Volunteer Infantry Regiment
• 18th Missouri Volunteer Infantry
• 18th New Hampshire Volunteer Infantry
• 18th New York Volunteer Infantry
• 18th North Carolina Infantry
• 18th Ohio Infantry
• 18th Regiment Alabama Infantry
• 18th Regiment Indiana Infantry
• 18th Regiment Kentucky Volunteer Infantry
• 18th Regiment Massachusetts Volunteer Infantry
• 18th Royal Hussars
• 18th U.S. Colored Infantry
• 18th Vermont Volunteer Infantry Regiment
• 18th Virginia Cavalry
• 18th Virginia Infantry
• 18th Wisconsin Volunteer Infantry Regiment
• Royal Irish Regiment (1684–1922)
• XVIII Corps (disambiguation)