James Hamilton, 6th Earl of Abercorn, PC (Ire) (c. 1661 – 28 November 1734), was a Scottish and Irish peer and politician.

Shortly after inheriting a Scottish and Irish peerage from a second cousin, he was created a viscount in Ireland for his services to the Williamite cause.

His father, James the elder, was a colonel in the English army, Hyde Park Ranger, and a groom of the bedchamber to Charles II of England.

On 6 June 1673 when he was about twelve years old, his father died from a wound received at a sea fight with the Dutch in the Third Anglo-Dutch War.

James and Elizabeth had 14 children nine sons: —and five daughters: Captain Hamilton's post in the bedchamber ended with the King's death in 1685.

On 21 March 1689 he[28] arrived at Derry from England with two ships: the frigate HMS Jersey and the merchantman Deliverance,[29] bringing gunpowder, munition, weapons, and £595 in cash.

He also brought the commission from King William and Queen Mary that confirmed Colonel Robert Lundy as Williamite governor of the town.

[32] After the end of the Williamite war in Ireland, he was elected as one of the two MPs for County Tyrone in the Irish House of Commons on 22 September 1692 and again on 12 August 1695.

About six months later, on 2 December 1701, Lord Abercorn was rewarded by King William with the titles of Viscount Strabane and Baron Mountcastle, both in the Peerage of Ireland.

[38] Abercorn died on 28 November 1734 at the age of 73[39] and was buried on 3 December in the Ormond vault of the Henry VII Chapel in Westminster Abbey.