James Hamilton, 6th Earl of Abercorn, PC (Ire) (c. 1661 – 28 November 1734) was a Scottish and Irish nobleman, the son of Colonel James Hamilton and Elizabeth Colepeper.
As Captain James Hamilton, he was appointed by James II to the Privy Council of Ireland, but deserted him for the cause of William, and served in the defence of Londonderry in 1689. He succeeded to his grandfather's baronetcy in 1697. Between 1692 and 1699, he represented Tyrone in the Irish House of Commons. Upon the death of his second cousin Charles in 1701, he succeeded as Earl of Abercorn, Baron Hamilton of Strabane, etc. but continued to live in Ireland. He was rewarded by William with the titles of Viscount Strabane and Baron Mountcastle, in the Peerage of Ireland, on 2 December 1701. He was a privy councillor in the reigns of Anne, George I, and George II.
He died 28 November 1734, and was buried in Henry VII Chapel in Westminster Abbey.
He married Elizabeth Reading, daughter of Sir Robert Reading, 1st Baronet, on 21 January 1684. They had the following children:
- James Hamilton, 7th Earl of Abercorn (1686–1744)
- Lady Elizabeth Hamilton, married on 2 January 1711 William Brownlow (died 1739), married in 1741 Martin, Comte de Kearnie
- The Hon. George Hamilton (died 1775), married and had issue
- Lady Mary Hamilton (born before 1704), married in 1719 Henry Colley
- Lady Jane Hamilton (before 1704 – 6 December 1753), married on 29 September 1719 Archibald Douglas-Hamilton (d. 1754)
- The Hon. Francis Hamilton (1700–1745), married and had issue
- The Hon. William Hamilton (1703–1721)
- The Hon. Charles Hamilton (1704–1786), married and had issue
- Lady Philippa Hamilton (died 27 January 1767), married Benjamin Pratt (d. 1721), married Michael O'Connell