The Beagle B.121 Pup is a 1960s British 2–4 seat single-engined training and touring aircraft built by Beagle Aircraft Limited at Shoreham Airport and Rearsby Aerodrome.

Beagle Aircraft Limited was a British light aircraft manufacturer. The company produced the Airedale, Terrier, Beagle 206, Husky and the Pup. It had factories at Rearsby in Leicestershire and Shoreham in Sussex. The company was dissolved in 1969.