Henry IV (1367-1413), King of England from 1399 to 1413, and the king from whom the Stanley lordship of Mann descends.

The Island came to him by forfeiture. William, Earl of Salisbury, had enjoyed it for seven years, and after his death it was sold in Richard II's time to Lord Scrope, who forfeited it to Henry IV by attainder. The King granted it on the nineteenth day of October in the first year of his reign to Henry Percy, Earl of Northumberland, for the term of his life. The Manx chronicle says that Percy was afterwards slain at the battle of Shrewsbury and that the King then gave the Isle of Man to Sir John Stanley, knight, Lieutenant of Ireland.

The Stanley grant is the one that lasted. The charter of 1406 recites the earlier gift to Percy and settles the Island on Sir John Stanley and his heirs, with the patronage of the bishopric, and it stayed in that family for two and a half centuries. The Manx antiquaries mark a change of style within it: Stanley and his heirs were called Kings of Mann until the second Earl Thomas, and Lords only after that.

The grant is the hinge of the Island's constitutional argument. It is the point at which the Island passed under an English title, and modern constitutional writing has used the same grant to argue that the Crown holds Mann as heir of Henry IV rather than by any descent from the Norse kings, with the later lordships of the Percys, the Stanleys and the Murrays subordinate to it.