Due to the saint's popularity, the name came into general use in medieval Europe, especially in Spain and France. It was also borne by a 16th-century king of Portugal who died in a crusade against Morocco.
A notable bearer was the American musician Miles Davis (1926-1991). In Scotland this name was historically used to Anglicize Maoilios.
This name was borne by a number of important saints, including Cyril of Jerusalem, a 4th-century bishop and Doctor of the Church, and Cyril of Alexandria, a 5th-century theologian. Another Saint Cyril was a 9th-century Greek missionary to the Slavs, who is credited with creating the Glagolitic alphabet with his brother Methodius in order to translate the Bible into Slavic. The Cyrillic alphabet, named after him, is descended from Glagolitic.
This name has been especially well-used in Eastern Europe and other places where Orthodox Christianity is prevalent. It came into general use in England in the 19th century.
The feminine name Adina 3 is from the same root, but is spelled differently in Hebrew.