John Wilson Croker (20 December 1780 – 10 August 1857) was an Irish and author.
He was born in Galway, the only son of John Croker, the surveyor-general of customs and excise in Ireland. He was educated at Trinity College, Dublin, where he graduated in 1800. Immediately afterwards he entered Lincoln's Inn, and in 1802 he was called to the Irish bar.
His interest in the French Revolution led him to collect a large number of valuable documents on the subject, which are now in the British Museum. In 1804 he published anonymously Familiar Epistles to J. F. Jones, Esquire, on the State of the Irish Stage, a series of caustic criticisms in verse on the management of the Dublin theatres. The book ran through five editions in one year. Equally successful was the Intercepted Letter from Canton (1805), also anonymous, a satire on Dublin society in the guise of a report on the manners of the Chinese at Quang-tchen on the "Li-fee". During this period a rather scathing poem attributed to Croker led to the suicide of actor John Edwin, husband of Elizabeth Rebecca Edwin. In 1807 he published a pamphlet on The State of Ireland, Past and Present, in which he advocated Catholic emancipation.
The following year (1808) Croker entered parliament as member for Downpatrick, obtaining the seat on petition, though he had been unsuccessful at the poll. The acumen displayed in his Irish pamphlet led Spencer Perceval to recommend him to the Duke of Wellington, who had just been appointed to the command of British forces in the Iberian Peninsula, as his deputy in the office of chief secretary for Ireland. This connection led to a friendship which remained unbroken till Wellington's death.