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 was Isaac Holroyd (1708–78), who lived at Dunamore in County Meath. John, the eldest son, first took the name of Baker on inheriting the estates of his uncle, Rev. Jones Baker, in 1768 and added Holroyd on the death of his own father in 1778.
Having served in the Army until 1763, he travelled for a while on the continent where he became close friends with the writer and historian Edward Gibbon, later the author of The History of the Decline and Fall of the Roman Empire. On his return he used his inherited wealth to buy in 1769 the country house of Sheffield Place in Sussex from Lord De La Warr. In 1780 he was elected to represent Coventry in the House of Commons, where he 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. As Irish peerages they did not interrupt his Parliamentary career and he was re-elected for Coventry in 1781 and for Bristol in 1790. His Parliamentary career did end however in 1802, when he was created a Peer of the United Kingdom as Baron Sheffield, of Sheffield in the County of York. In 1816, he was also created Viscount Pevensey and Earl of Sheffield in the Peerage of Ireland.