Sir William Grey Ellison-Macartney, KCMG (7 June 1852 – 4 December 1924) was an Irish-born British politician, who also served as the Governor of the Australian states of Tasmania and Western Australia.

In January 1886, he convened a meeting which led to the formation of the Irish Unionist Party, for which he served as whip.

Hoping to reassert his place in the loyalist hierarchy, Ellison-Macartney led a "law-and-order" campaign, targeted in particular at the violence and agrarian crime committed by William O'Brien's United Irish League.

[3] Ellison-Macartney was appointed Deputy-Master of the Royal Mint in January 1903,[5] serving to 1913,[2] and was High Sheriff of Antrim in 1908.

[7] With Earle and his ministry sworn in, neither side desired to hold an election so parliament remained in session, with Ellison-Macartney's recommendations over-ridden by the Secretary of State for the Colonies.

His term in Western Australia was not a happy one – his critical comments about Tasmanian politicians had made Western Australians wary of his attitude, and he had to deal with the state's post-First World War economic depression and continued objection to his Unionist stance from those supportive of Irish Home Rule.

On 5 August 1897, he married Ettie Myers Scott at Holcombe, Somerset, and they had three children: daughters Phoebe (b.1898) and Mildred (b.1900) and a younger son John; Phoebe died in 1918, aged 20, as a result of a riding accident while the family lived were living in Perth, Australia.