Royal Engineer tunnelling companies were specialist units of the Corps of Royal Engineers within the British Army formed to dig attacking tunnels under enemy lines during the First World War.

The Corps of Royal Engineers, usually called the Royal Engineers (RE), and commonly known as the Sappers, is the engineering arm of the British Army. It provides military engineering and other technical support to the British Armed Forces and is headed by the Chief Royal Engineer. The Corps Headquarters and the Royal School of Military Engineering are in Chatham in Kent, England. The corps is divided into several regiments, barracked at various places in the United Kingdom and around the world.