William North, 6th Baron North and 2nd Baron Grey (22 December 1678 – 31 October 1734), known as Lord North and Grey, was an English soldier and Jacobite, and a peer for more than forty years. He had the right to sit in the House of Lords between 1698 and 1734, although he spent the last twelve years of his life overseas.
North and Grey was the first of his family to become a professional soldier, and he rose to the rank of Lieutenant General. His career faltered after the death of Queen Anne because he was known to be a Jacobite. After being arrested for his part in the Atterbury Plot, but released for lack of evidence, North and Grey took service in the army of King Philip V of Spain. He died in Madrid.
North was born in Caldecot, Cambridgeshire, the son of Charles North, 5th Baron North (c. 1636–1691), by his marriage to a daughter of the first Baron Grey of Warke. He was the grandson of Dudley North, 4th Baron North (1602–1677). Four years before the death of his grandfather, his father had been created a peer in his own right and summoned to the House of Lords as Baron Grey of Rolleston, so that North inherited both titles on his father's death in 1691 and was known as Lord North and Grey.
He came of a more intellectual family than most peers of his day. His uncle Francis North became Lord Chancellor as Lord Guilford, while other uncles were Sir Dudley North, an economist, John North, master of Trinity College, Cambridge, and Roger North, a historian.