Algernon Percy, 4th Duke of Northumberland (15 December 1792 - 12 February 1865) was a British aristocrat and Conservative politician, who briefly served as First Lord of the Admiralty in Lord Derby's first government.

The younger son of the 2nd Duke, he succeeded his brother in 1847. He married Lady Eleanor Grosvenor, a daughter of the 2nd Marquess of Westminster, but had no children, and was succeeded in his title by his cousin, the 2nd Earl of Beverley.