This was a common name in classical Greece, and, due to both the saints who carried it and the favourable meaning, it came into general use in the Christian world, being especially popular among Eastern Christians. It was however rare in Britain before the 19th century. Famous bearers include three tsars of Russia (in the Russian form Fyodor) and American president Theodore Roosevelt (1858-1919).
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.
Due to the renown of the saints by this name, Gregory (in various spellings) has remained common in the Christian world through the Middle Ages and to the present day. It has been used in England since the 12th century. A famous bearer from the modern era was American actor Gregory Peck (1916-2003).
The spelling was later altered to Cordelia when Geoffrey's story was adapted by others, including Edmund Spenser in his poem The Faerie Queene (1590) and Shakespeare in his tragedy King Lear (1606).