Agnes f. Greek ἁγνή 'pure, chaste'.
The name of a 3rd C saint, an 11th C queen consort of France, an 11th C queen of Castille and Leon, an 11th C queen of Aragon and Navarre, an 11th C Holy Roman empress, a 12th C queen of Aragon, a 12th C Italian saint, a 12th C queen consort of Hungary, a 12th C queen consort of Jerusalem, a 13th C queen consort of Denmark, and a 13th C Byzantine empress.
The popularity of Saint Agnes of Rome (3rd C) contributed to this name's enduring popularity throughout all of Europe and all of the Middle Ages.