A family of marcher lords of medieval England with lands in Northumberland. Henry de Percy (1341–1408), 1st Earl of Northumberland, was the first of the family to be of major importance in the defence of England’s northern frontier. The earl’s son, Sir Henry Percy (‘Hotspur’) (1364–1403), was a hero of the Battle of Otterburn. When Henry of Bolingbroke landed in the north of England in 1399, the earl and Hotspur helped assure him of the crown; they were well rewarded, but within four years their greed for more offices or money led them into open rebellion. Hotspur and his uncle Thomas, Earl of Worcester, were killed at Shrewsbury in 1403. Five years later Earl Henry invaded England from Scotland, but he too was killed and his estates were forfeited.

Subsequently restored to their estates, later generations of the family resumed their role as guardians of the northern frontier and rivals of the Nevilles. The male line ended in 1670, but the earldom passed in the female line to Sir Hugh Smithson (1715–86) who took the name of Percy and in 1766 was created Duke of Northumberland.