As an English name it can also derive from the month of August, which was named for the Roman emperor Augustus.
Due to its favourable meaning, this name was popular among early Christians, being borne by many early saints and four popes. It has been used in England since the Middle Ages, though it has been more popular in continental Europe. A notable bearer was the German composer Felix Mendelssohn (1809-1847).
This is the Old Irish form of the name, as well as the usual Anglicized form of Modern Irish Fearghas or Fearghus.
This name was popularized in continental Europe by the works of the 18th-century Scottish poet James Macpherson [1]. Napoleon was an admirer of Macpherson, and he suggested Oscar as the second middle name of his godson, who eventually became king of Sweden as Oscar I. Other notable bearers include the Irish writer and humorist Oscar Wilde (1854-1900) and the Brazilian architect Oscar Niemeyer (1907-2012).
This name has never been common in the English-speaking world, though it has been well-used elsewhere in Europe. A famous bearer was the Italian Renaissance master Raffaello Sanzio (1483-1520), usually known simply as Raphael in English.
As a given name, it has traditionally been more masculine than feminine. In America however, after the variant Sydney became popular for girls, Sidney was used more for girls than boys between 1993 and 2019.
A famous bearer of the name was the English courtier, poet and explorer Walter Raleigh (1552-1618). It was also borne by Walter Scott (1771-1832), a Scottish novelist who wrote Ivanhoe and other notable works.