Due to the renown of the apostle, this name became common throughout the Christian world (in various spellings). In England the Normans introduced it in the Old French form Piers, which was gradually replaced by the spelling Peter starting in the 15th century [1].
Besides the apostle, other saints by this name include the 11th-century reformer Saint Peter Damian and the 13th-century preacher Saint Peter Martyr. It was also borne by rulers of Aragon, Portugal, and Russia, including the Russian tsar Peter the Great (1672-1725), who defeated Sweden in the Great Northern War. Famous fictional bearers include Peter Rabbit from Beatrix Potter's children's books, Peter Pan, the boy who refused to grow up in J. M. Barrie's 1904 play, and Peter Parker, the real name of the comic book superhero Spider-Man.
It has been used as a Christian given name in the English-speaking world since the Protestant Reformation. A famous bearer was Nathan Hale (1755-1776), an American spy executed by the British during the American Revolution.
As an English Christian name, Isaac was occasionally used during the Middle Ages, though it was more common among Jews. It became more widespread after the Protestant Reformation. Famous bearers include the physicist and mathematician Isaac Newton (1643-1727) and the science-fiction writer Isaac Asimov (1920-1992).