This name was borne by the heroine of Lewis Carroll's novels Alice's Adventures in Wonderland (1865) and Through the Looking Glass (1871).
This is also the name of an Irish county, which was itself probably derived from Irish clár meaning "plank, level surface".
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.
It has never been very common as a given name in the English-speaking world, though it rose in popularity after the middle of the 20th century. In the United States it is frequently an African-American name. In Lithuania it may be given in honour of the Lithuanian-American aviator Steponas Darius (1896-1933), who died attempting to fly nonstop from New York to Lithuania. His surname was an Americanized form of the original Darašius.
In America, this name received boosts in popularity from main characters in the movies The Jackal (1997) and Leap Year (2010).
Because Elijah was a popular figure in medieval tales, and because his name was borne by a few early saints (who are usually known by the Latin form Elias), the name came into general use during the Middle Ages. In medieval England it was usually spelled Elis. It died out there by the 16th century, but it was revived by the Puritans in the form Elijah after the Protestant Reformation. The name became popular during the 1990s and 2000s, especially in America where it broke into the top ten in 2016.
This name was also borne by a powerful 10th-century ruler of Bulgaria who expanded the empire to its greatest extent.