R101 was one of a pair of British rigid airships completed in 1929 as part of the Imperial Airship Scheme, a British government programme to develop civil airships capable of service on long-distance routes within the British Empire. It was designed and built by an Air Ministry–appointed team and was effectively in competition with the government-funded but privately designed and built R100. When built, it was the world's largest flying craft at 731 ft (223 m) in length, and it was not surpassed by another hydrogen-filled rigid airship until the LZ 129 Hindenburg was launched seven years later.

A rigid airship is a type of airship in which the envelope is supported by an internal framework rather than by being kept in shape by the pressure of the lifting gas within the envelope, as in blimps and semi-rigid airships. Rigid airships are often commonly called Zeppelins, though this technically refers only to airships built by the Luftschiffbau Zeppelin company.