Humphrey of Lancaster, Duke of Gloucester was an English prince, soldier and literary patron. He was "son, brother and uncle of kings", being the fourth and youngest son of Henry IV of England, the brother of Henry V, and the uncle of Henry VI. Gloucester fought in the Hundred Years' War and acted as Lord Protector of England during the minority of his nephew. A controversial figure, he has been characterised as reckless, unprincipled, and fractious, but is also noted for his intellectual activity and for being the first significant English patron of humanism, in the context of the Renaissance.

Lord Protector was a title that has been used in British constitutional law for the head of state. It was also a particular title for the British heads of state in respect to the established church. It was sometimes used to refer to holders of other temporary posts; for example, a regent acting for the absent monarch.