William Northey FRS (c. 1722 – 24 December 1770) was an English politician who sat in the House of Commons from 1747 to 1770.
Northey was the son of William Northey of Ivey House, Compton Basset, Wiltshire and his wife Abigail Webster daughter of Sir Thomas Webster, 1st Baronet of Battle Abbey, Sussex. His father was MP for Calne in 1713, and for Wooton Bassett in 1714.
Northey was elected a Member of Parliament (MP) for Calne on 27 June 1747 and held the seat until 1761. He was then elected MP for Maidstone, Kent on 28 March 1761 and held the seat until 18 March 1768. He was lastly elected MP for Great Bedwyn on 13 November 1768 and held the seat until his death in 1770. He was described as a leading and eloquent member of the opposition in parliament.
Northey was a lieutenant-colonel in the Wiltshire county militia and one of the commissioners for trade. He became a Fellow of the Royal Society on 21 June 1753. He was Groom of the Chamber to King George III.
Northey married Anne Hopkins, daughter of Edward Hopkins, MP, Secretary of State for Ireland. His son William was also an MP.