In England and elsewhere in Europe during the Middle Ages this name was used in honour of the saint. However, it was not generally given in Ireland before the 17th century because it was considered too sacred for everyday use. It has since become very common there.
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).
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.