Henry de Percy, 1st Baron Percy

Henry de Percy
Ordinancer
Seal of Henry Percy from the Barons' Letter, 1301. On his shield he bears the arms of Brabant (Percy modern)
Successor	Henry de Percy, 2nd Baron Percy
Born	25 March 1273 Petworth
Died	October 1314 (aged 41) Alnwick

Henry de Percy, 1st Baron Percy of Alnwick (1273–1314) was a medieval English magnate.

He fought under King Edward I of England in Wales and Scotland and was granted extensive estates in Scotland, which were later retaken by the Scots under King Robert I of Scotland. He added Alnwick to the family estates in England, founding a dynasty of northern warlords. He rebelled against King Edward II over the issue of Piers Gaveston and was imprisoned for a few months. After his release, he declined to fight under Edward II at the Battle of Bannockburn, remaining at Alnwick, where he died a few months later, aged 41.

Henry was born at Petworth in Sussex on 25 March 1273, seven months after his father's death, saving the family line from extinction, as two older brothers had died in infancy, and all six uncles had died without leaving any legitimate heir. He was fortunate in having the powerful John de Warenne, 6th Earl of Surrey as his maternal grandfather. Henry was the son of Henry de Percy (d.1272), 7th feudal baron of Topcliffe, Yorkshire, by his wife, Eleanor de Warenne, daughter of John de Warenne, 6th Earl of Surrey by Alice de Lusignan, Countess of Surrey, half sister of King Henry III. His great-great-grandfather was Jocelin de Louvain (d.1180) who had married Agnes de Percy (d.1203), one of the two daughters and co-heiresses of William II de Percy (d.1174/5), 3rd feudal baron of Topcliffe, whose descendants had adopted the surname "de Percy".

In 1293 Henry came into his inheritance of estates in Sussex and Yorkshire, including Topcliffe Castle, the ancient family seat. In 1294 he married Eleanor, daughter of the Earl of Arundel. He then proceeded to change the family coat of arms from Azure, five fusils in fess or ("Percy ancient") to Or, a lion rampant azure ("Percy modern")(a blue lion rampant on a gold background). Blue and gold were the Earl Warenne's colours and a gold lion rampant had been the Arundel's arms. Alternatively the arms are said to be the arms of Brabant. This emphasised his royal and noble connections and marked his ambition. This was also the year he went to war for the first time, summoned to fight in France, but then diverted to Wales to join Edward I in suppressing a Welsh rebellion. There he learned the grim business of medieval warfare, and command and supply of armies in the field.