In England the name was used by the Normans and became very popular due to Saint Thomas Becket, a 12th-century archbishop of Canterbury and martyr. It was reliably among the top five most common English names for boys from the 13th to the 19th century, and it has remained consistently popular to this day.
Another notable saint by this name was the 13th-century Italian philosopher and theologian Thomas Aquinas, who is regarded as a Doctor of the Church. Other famous bearers include philosopher Thomas Hobbes (1588-1679), American president Thomas Jefferson (1743-1826), novelist Thomas Hardy (1840-1928), and inventor Thomas Edison (1847-1931).
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.
American writers Jack London (1876-1916) and Jack Kerouac (1922-1969) were two famous bearers of this name. It is also borne by the actor Jack Nicholson (1937-) and the golfer Jack Nicklaus (1940-). Apart from Nicklaus, none of these famous bearers were given the name Jack at birth.
In the United Kingdom this form has been bestowed more frequently than John since the 1990s, being the most popular name for boys from 1996 to 2008.
Famous bearers include the Welsh poet Dylan Thomas (1914-1953) and the American musician Bob Dylan (1941-), real name Robert Zimmerman, who took his stage surname from the poet's given name. Due to those two bearers, use of the name has spread outside of Wales in the last half of the 20th century. It received a further boost in popularity in the 1990s due to a character on the television series Beverly Hills 90210.
Due to the popularity of the biblical character, the name came into use in England during the Middle Ages. Though it became rare by the 15th century, it was revived after the Protestant Reformation. Famous bearers of this name include English author Daniel Defoe (1660-1731), Swiss mathematician Daniel Bernoulli (1700-1782), and American frontiersman Daniel Boone (1734-1820).
This is also the name of an Irish county, which was itself probably derived from Irish clár meaning "plank, level surface".
As an English name, Caleb came into use after the Protestant Reformation. It was common among the Puritans, who introduced it to America in the 17th century.