Sir Beauchamp St John (17 March 1594–1667) was an English politician who sat in the House of Commons variously between 1621 and 1653. He supported the Parliamentary side in the English Civil War. St John was a son of Oliver St John, 3rd Baron St John of Bletso and his wife Dorothy Reid, daughter of Sir John Rede or Reid, of , Gloucestershire. He was admitted fellow commoner at Queens' College, Cambridge on 9 March 1609/10, and was conferred an MA in 1612/3, on the occasion of the King's visit. On 5 May 1613, he was admitted to Lincoln's Inn. He was knighted on 24 July 1619 at Bletsoe together with his brother Henry, later an MP. Apart from Henry, four other brothers, Oliver, Rowland, Anthony and Alexander were all to become MPs.