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 got more popular in the early 1980s, then got a boost in 1990 when it was used by the main character in the movie Days of Thunder.
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.