Titles:
Baron Percy (1299 cr - 4th)  
Earl of Northumberland (1377 cr - 1st)

Henry Percy, 1st Earl of Northumberland (November 10, 1341 – February 20, 1408), was the son of Henry de Percy, 3rd Baron Percy, and the father of Henry "Harry Hotspur" Percy. His mother was Mary of Lancaster, daughter of Henry Plantagenet, 3rd Earl of Leicester, son Edmund Crouchback, son of Henry III of England.

Originally a follower of Edward III of England, for whom he held high offices in the administration of northern England, Henry Percy went on to support King Richard II. He was given the title of Marshal of England and created an earl at Richard's coronation (1377), but he switched to the side of Henry Bolingbroke (later, Henry IV) after Richard created his chief rival, Ralph Neville, 1st earl of Westmorland in 1399. On Henry's coronation he was appointed Constable of England and granted the lordship of the Isle of Man. In 1403 Percy turned against Henry IV in favor of Edmund Mortimer, 5th Earl of March, and then conspired with Owen Glendower against King Henry. This rebellion failed at the Battle of Shrewsbury but, since Percy did not directly participate, he lost his office as Constable but was not convicted of treason. But in 1405 Percy supported Richard le Scrope, archbishop of York, in another rebellion, and then Percy fled to Scotland, and his estates were confiscated by the king. In 1408 Percy invaded England and was killed at the Battle of Branham Moor.

Northumberland is a major character in Shakespeare's Richard II, Henry IV, part 1, and Henry IV, part 2.