Sir Henry Percy KG (20 May 1364 – 21 July 1403), commonly known as Sir Harry Hotspur, or simply Hotspur, was a late-medieval English nobleman.
 He was a significant captain during the Anglo-Scottish wars.
 He later led successive rebellions against Henry IV of England and was slain at the Battle of Shrewsbury in 1403 at the height of his career.
Henry Percy, Baron Percy of Alnwick (died 1659), son of Henry Percy, 9th Earl of Northumberland, sat in the Short Parliament as the member for Portsmouth, and in the Long Parliament an M.P. for Northumberland; an originator of the "first army plot" in 1641, after which he retired to France.
 He was appointed general of the ordnance of the king's army and created baron, 1643; but fell in disgrace in 1644 through his desire for peace.
 In 1648 he resigned his command and went to France where he joined
Henry IV (15 April 1367 – 20 March 1413), also known as Henry of Bolingbroke ( ), was King of England and Lord of Ireland from 1399 to 1413, and asserted the claim of his grandfather, Edward III, to the Kingdom of France.
The Battle of Bramham Moor on 19 February 1408 was the final battle in the Percy Rebellion of 1402 – 1408, which pitted Henry Percy, 1st Earl of Northumberland, leader of the wealthy and influential Percy family, against the usurper King of England, King Henry IV.
 The Percys had previously aided Henry IV in his coup d'etat against his cousin King Richard II in 1399.
Thomas Percy, 1st Baron Egremont (29 November 1422, in Leconfield, Yorkshire – 10 July 1460, at the Battle of Northampton) was the son of Henry Percy, 2nd Earl of Northumberland and Lady Eleanor Neville, being made Lord Egremont in 1449.
 A northern baron, he became a leading figure in the internecine Percy-Neville feud, fighting at the Battle of Heworth Moor.
 When the Wars of the Roses began mid-decade, Egremont fought for the king on the Lancastrian side, being killed six years later at the battle of Northampton.
Henry Percy, 2nd Earl of Northumberland (3 February 1393 – 22 May 1455) was an English nobleman and military commander in the lead up to the Wars of the Roses.
 He was the son of Henry "Hotspur" Percy, and the grandson of Henry Percy, 1st Earl of Northumberland.
 His father and grandfather were killed in different rebellions against Henry IV in 1403 and 1408 respectively, and the young Henry spent his minority in exile in Scotland.
 Only after the death of Henry IV in 1413 was he reconciled with the Crown, and in 1416 he was created Earl of Northumberland.
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 descendant 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.
William Thirning KS (died 1413) was a British justice.
 He served as a commissioner of the peace in 1377 in Northamptonshire and as a commissioner of Oyer and terminer in Bedfordshire in the same year, as well as a Justice of Assize for Yorkshire, Northumberland, Cumberland and Westmorland in June 1880 before becoming a Serjeant-at-law in 1383.
 He was made a King's Serjeant in 1388, and a justice of the Court of Common Pleas on 11 April of the same year, becoming Chief Justice on 15 January 1396.
 Thirning took a leading role in the deposition of Richard II 1399, obtaining his renunciation of the throne on 29 September and announcing it in Parliament the following day, before personally announcing the sentence to Richard on 1 October.
 He continued to be Chief Justice throughout the reign of Henry IV and was reappointed by Henry V when he took the throne in 1413; he died soon after, as his successor was appointed on 26 June.
John Holland, 1st Duke of Exeter (c. 1352 – 16 January 1400) also 1st Earl of Huntingdon, was an English nobleman, a half-brother of King Richard II (1377–1399), to whom he remained strongly loyal.
 He is primarily remembered for being suspected of assisting in the downfall of King Richard's uncle Thomas of Woodstock, 1st Duke of Gloucester (1355–1397) (youngest son of King Edward III) and then for conspiring against King Richard's first cousin and eventual deposer, Henry Bolingbroke, later King Henry IV (1399–1413).
Isabel le Despenser, Countess of Worcester and Warwick, LG (26 July 1400 – 1439) was the posthumous daughter and eventually the sole heiress of Thomas le Despenser, 1st Earl of Gloucester (died 1399) by his wife, Constance of York.
 She was born six months after her father had been beheaded for plotting against King Henry IV (1399–1413).

Question: Henry Percy's father and grandfather were killed in rebellions against what King of England who was also the Lord of Ireland from 1399-1413?
Answer: Henry IV