John William Ellison-Macartney (1818 – 13 February 1904), born John William Ellison, was an Irish barrister and Conservative politician. From 1874 to 1885 he was Member of Parliament (MP) for Tyrone (UK Parliament constituency), taking his seat in the House of Commons of the United Kingdom of Great Britain and Ireland.
Ellison-Macartney was called to the bar in 1846, and to the Irish Bar in 1848. In 1870 he was High Sheriff of County Armagh.
Ellison-Macartney first stood for Parliament at the Tyrone by-election in 1873 after the death of Henry T. Lowry-Corry. He narrowly lost that contest (by 3103 votes to 3139) to his sole opponent, the Conservative Henry W. Lowry-Corry (a nephew of the deceased MP); the Liberals had not fielded a candidate in Tyrone since 1852. At the 1874 general election, Tyrone's two seats were contested by three Conservatives, and Ellison-Macartney topped the poll by a wide margin, unseating the sitting MP Lord Claud Hamilton. He was re-elected in 1880, and held the seat until the Redistribution of Seats Act divided the Tyrone constituency into four new single-member divisions for the 1885 general election. He did not stand again. He was also a member of The Apprentice Boys of Derry Parent Club.