The name was mainly confined to Spain and Portugal during the Middle Ages. After the 16th century it was spread to other parts of the Christian world, due to the fame of the Spanish nun and reformer Saint Teresa of Ávila. Another famous bearer was the Austrian Habsburg queen Maria Theresa (1717-1780), who inherited the domains of her father, the Holy Roman emperor Charles VI, beginning the War of the Austrian Succession.
Due to the saint's popularity, the name came into general use in medieval Europe, especially in Spain and France. It was also borne by a 16th-century king of Portugal who died in a crusade against Morocco.
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.
In England Oliver was a common medieval name, however it became rare after the 17th century because of the military commander Oliver Cromwell, who ruled the country following the civil war. The name was revived in the 19th century, perhaps due in part to the title character in Charles Dickens' novel Oliver Twist (1838), about a poor orphan living on the streets of London. It became very popular at the beginning of the 21st century, reaching the top rank for boys in England and Wales in 2009 and entering the top ten in the United States in 2017.
Geoffrey based parts of Merlin's character on Myrddin Wyllt, a legendary madman and prophet who lived in the Caledonian Forest. Other parts of his life were based on that of the historical 5th-century Romano-British military leader Ambrosius Aurelianus (also known as Emrys Wledig). In Geoffrey's version of the tales and later embellishments Merlin is a magician and counselor for King Arthur.
This name was initially more common among Eastern Christians in the Byzantine Empire, but it flourished in Western Europe after the First Crusade. In England it became extremely popular, typically being the most common male name from the 13th to the 20th century (but sometimes outpaced by William). During the later Middle Ages it was given to approximately a fifth of all English boys. In the United States it was the most common name for boys until 1923.
The name (in various spellings) has been borne by 21 popes and eight Byzantine emperors, as well as rulers of England, France, Sweden, Denmark, Poland, Portugal, Bulgaria, Russia and Hungary. It was also borne by the poet John Milton (1608-1674), philosopher John Locke (1632-1704), American founding father and president John Adams (1735-1826), and poet John Keats (1795-1821). Famous bearers of the 20th century include author John Steinbeck (1902-1968), assassinated American president John F. Kennedy (1917-1963), and musician John Lennon (1940-1980).
The forms Ian (Scottish), Sean (Irish) and Evan (Welsh) have also been frequently used in the English-speaking world, as has the medieval diminutive Jack.
The Cornish form of this name, Jennifer, has become popular in the English-speaking world.
Gawain was a popular hero in medieval tales such as those by Chrétien de Troyes, where his name appears in the French form Gauvain or Gauvains. He is the main character of the 14th-century anonymous poem Sir Gawain and the Green Knight, in which he accepts a potentially fatal challenge from the mysterious Green Knight.
Because Elijah was a popular figure in medieval tales, and because his name was borne by a few early saints (who are usually known by the Latin form Elias), the name came into general use during the Middle Ages. In medieval England it was usually spelled Elis. It died out there by the 16th century, but it was revived by the Puritans in the form Elijah after the Protestant Reformation. The name became popular during the 1990s and 2000s, especially in America where it broke into the top ten in 2016.