Percy, the name of an English historical family, descended from William de Percy, who derived his name from the village of Percy in lower Normandy. He accompanied William the Conqueror to England in 1066, became a feudal lord, and died near Jerusalem in the crusade of 1096-'9. With the death of the third baron in the reign of Henry II. the male line of Percy became extinct. His granddaughter Maud married the earl of Warwick and died without issue. Her sister Agnes married Jocelin of Louvain, who took the surname of Percy. Henry de Percy in the reign of Edward I. acquired the barony of Alnwick. The third Henry of Alnwick in the reign of Edward III. married Mary, daughter of Henry, earl of Lancaster and grandson of Henry III., and Richard II. in 1377 created one son by this marriage earl of Northumberland and another earl of Worcester. The son of this earl of Northumberland was Henry Percy (born May 20,1364), the famous Hotspur of history, who rebelled with his father against Henry IV., and was killed at the battle of Shrewsbury in July, 1403. His uncle was beheaded soon after the battle, and the earldom of Worcester became extinct.

His father was killed by the posse comitatus of Yorkshire in 1408. In 1414 Henry V. restored the earldom to Hotspur's son Henry, who was killed in the battle of St. Albans in 1455. The third earl was killed in the battle of Towton in 1461 The fourth earl was murdered in 1489, with some of his attendants, in Cock-ledge, Yorkshire, by the populace, who called upon him to present their grievances on the subject of taxation. The fifth earl took part in Henry VIII.'s French campaign (1513), and died in 1527. The sixth earl, Henry Algernon, dying without issue in 1537, and his brother, Sir Thomas Percy, having been attainted and executed, Edward VI. in 1551 conferred the title of duke of Northumberland upon John Dudley, earl of Warwick (see Dudley); but after he perished on the scaffold, Queen Mary in 1557 created Thomas, son of the attainted Sir Thomas, earl of Northumberland, with remainder to Henry his brother. He conspired against Elizabeth, was beheaded at York in 1572, and would have been attainted but for the reversion in favor of his brother, who succeeded as eighth earl. He was committed to the tower for alleged participation in a supposed plot in favor of Mary, queen of Scots, and was found dead in his bed there, June 21, 1585, having been shot with three bullets from a pistol.

His son Henry, ninth earl, after an ineffectual attempt to involve him in the gunpowder plot (1605), was fined £30,000 and imprisoned for several years in the tower. His son Algernon, tenth earl, took an active part during the rebellion against Charles I., but subsequently favored the restoration. Josceline, eleventh earl, died in 1670 without male issue, and the title became extinct. In 1674 Charles II. created George Fitzroy, his natural son by the duchess of Cleveland, earl and afterward duke of Northumberland, but he died without issue in 1716, and the title again became extinct. In the mean time Elizabeth, daughter of the eleventh earl, was in her own right Baroness Percy, and her husband, Henry Cavendish, earl of Ogle and son of the duke of Newcastle, assumed the surname of Percy, but died without issue. Elizabeth then married Charles Seymour, duke of Somerset, and the eldest son of that marriage, on the death of his mother in 1722, took his seat in the house of lords as Baron Percy. He inherited the dukedom of Somerset in 1741, and was created earl of Northumberland in 1749, with remainder to Sir Hugh Smithson, who had married his only surviving daughter, Elizabeth Seymour. Sir Hugh succeeded to the title on the death of his father-in-law in 1750, obtaining from parliament permission to assume the surname and arms of Percy. . In 1766 he was created Earl Peroy and duke of Northumberland. The fourth duke (born Dec. 15, 1792, died Feb. 12, 1865), a distinguished naval officer and man of science, was president of the royal institution, and in 1852 became first lord of the admiralty.

At his death his title passed to his cousin, George Percy, second earl of Beverley. He died Aug. 22,1867, and was succeeded by his son, Algernon George, born May 2, 1810, the sixth and present duke of Northumberland. Northumberland house, Charing Cross, long one of the historical mansions of London, was sold in 1873 for about £500,000 to the board of public works, to be pulled down for the purpose of opening a new street, and the duke devoted a portion of the purchase money to the embellishment of Trafalgar square.