John Baker-Holroyd, 1st Earl of Sheffield (21 December 1735 - 30 May 1821) was an English politician who came from a Yorkshire family, a branch of which had settled in the Kingdom of Ireland.
His grandfather was Isaac Holroyd (1643-1706), a merchant who emigrated to Ireland after the Restoration. His father Isaac (1708-78) lived at Dunamore in County Meath.
He inherited considerable wealth, and in 1769 bought Sheffield Place in Sussex from Lord De La Warr. Having served in the Army, he entered the House of Commons in 1780, and in that year was prominent against the anti-Catholic Lord George Gordon and the Gordon rioters.
In 1781 he was created a Peer of Ireland as Baron Sheffield, of Dunamore in the County of Meath, and in 1783 was further created Baron Sheffield, of Roscommon in the County of Roscommon, with a special remainder in favour of his daughters. In 1802 he was created a Peer of the United Kingdom as Baron Sheffield, of Sheffield in the County of York. In 1816, he was created Viscount Pevensey and Earl of Sheffield in the Peerage of Ireland. He was a great authority on farming, and in 1803, he was appointed President of the Board of Agriculture. But he is remembered chiefly as the close friend and literary executor of Edward Gibbon (author of "The History of the Decline and Fall of the Roman Empire"), whose Memoirs and other miscellaneous works he subsequently edited and published.
He married Abigail Way, daughter of Lewis Way of Richmond, Surrey and they had two children. Abigail died in 1793 and he remarried to Lady Anne North (1782?-18 January 1832), the daughter of the former Prime Minister Lord North on 20 January 1798. His son and grandson succeeded as second and third Earls of Sheffield, the latter being a well-known patron of cricket, at whose death the earldom became extinct.
His daughter Maria Josepha married John Stanley, 1st Baron Stanley of Alderley in 1796, and therefore the Irish barony, under special remainder, later passed to Edward Stanley, 4th Baron Stanley of Alderley, who thus became also fourth Baron Sheffield.