20th Regiment may refer to:
Infantry regiments 20th Infantry Regiment (United States) 20th Regiment of Bengal Native Infantry, an East India Company unit 20th Duke of Cambridge's Own Infantry (Brownlow's Punjabis), a British Indian Army unit 20th Continental Regiment, a Continental Army unit 20th Regiment of Foot, a British Army unit
American Civil War regiments Union (Northern) regiment 20th Connecticut Infantry Regiment 20th Illinois Infantry Regiment 20th Indiana Infantry Regiment 20th Iowa Infantry Regiment 20th Kansas Militia Infantry Regiment 20th Kentucky Infantry Regiment 20th Maine Infantry Regiment 20th Massachusetts Infantry Regiment 20th Michigan Infantry Regiment 20th New York Infantry Regiment 20th Pennsylvania Infantry Regiment 20th Wisconsin Infantry Regiment
Confederate (Southern) regiments 20th Arkansas Infantry Regiment 20th Tennessee Infantry Regiment 20th Virginia Infantry Regiment
Other regiments 20th Marine Regiment (United States) 20th Field Artillery Regiment, RCA, Royal Canadian Artillery 20th Field Artillery Regiment (United States) 20th Hussars, a cavalry regiment of the British Army 20th Lancers (Pakistan), an armoured regiment 20th Light Dragoons, a cavalry regiment of the British Army 20th Surveillance and Target Acquisition Regiment, Royal Australian Artillery