Saints bearing the name include an 8th-century musician in the court of Charlemagne and an 11th-century French bishop who is the patron saint of brewers. It was also borne by Arnold of Brescia, a 12th-century Augustinian monk who rebelled against the Church and was eventually hanged. Famous modern bearers include American golfer Arnold Palmer (1929-2016) and Austrian-American actor and politician Arnold Schwarzenegger (1947-).
Arthur is the name of the central character in Arthurian legend, a 6th-century king of the Britons who resisted Saxon invaders. He may or may not have been based on a real person. He first appears in Welsh poems and chronicles (perhaps briefly in the 7th-century poem Y Gododdin and more definitively and extensively in the 9th-century History of the Britons [1]). However, his character was not developed until the chronicles of the 12th-century Geoffrey of Monmouth [2]. His tales were later taken up and expanded by French and English writers.
The name came into general use in England in the Middle Ages due to the prevalence of Arthurian romances, and it enjoyed a surge of popularity in the 19th century. Famous bearers include German philosopher Arthur Schopenhauer (1788-1860), mystery author and Sherlock Holmes creator Arthur Conan Doyle (1859-1930), and science-fiction author Arthur C. Clarke (1917-2008).
This name was initially more common among Eastern Christians, though it came to the West by the Middle Ages. It was borne by six kings of France and five kings of Spain. It was regularly used in England during the Middle Ages, although the Spanish king Philip II, who attempted an invasion of England, helped make it less common by the 17th century. It was revived in the English-speaking world in the 19th century. Famous bearers include the Elizabethan courtier and poet Philip Sidney (1554-1586) and the American science fiction novelist Philip K. Dick (1928-1982).