Basil m. Greek βασιλεύς 'king'.
The name of four 4th C saints, an 8th C saint, a 9th C Byzantine emperor, a 10th C Byzantine emperor, an 11th C Byzantine emperor, a 14th C emperor of Trebizond, a 14th C grand prince of Moscow, two 15th C grand princes of Moscow, a 16th C Russian saint, and a 16th C Russian czar.