Algernon Percy, 10th Earl of Northumberland, 4th Baron Percy,, was an English aristocrat, and supporter of the Parliamentary cause in the First English Civil War.

Henry Percy, 9th Earl of Northumberland, KG was an English nobleman. He was a grandee and one of the wealthiest peers of the court of Elizabeth I. Under James I, Northumberland was a long-term prisoner in the Tower of London, due to the suspicion that he was complicit in the Gunpowder Plot. He is known for the circles he moved in as well as for his own achievements. He acquired the sobriquet The Wizard Earl, from his scientific and alchemical experiments, his passion for cartography, and his large library.