Henry Percy 1st Earl of Northumberland 4th Baron Percy titular King of Mann KG Lord Marshal (10 November 1341 – 20 February 1408) was the son of Henry de Percy 3rd Baron Percy and a descendent of Henry III of England. His mother was Mary of Lancaster daughter of Henry 3rd Earl of Lancaster son of Edmund Earl of Leicester and Lancaster who was the son of Henry III. Henry Percy married Margaret Neville daughter of Ralph Neville 2nd Baron Neville de Raby and Alice de Audley.
