Кирила, also known as Cyril, was a 9th-century Byzantine scholar and missionary. He is best known for creating the Glagolitic alphabet, which was the first alphabet used to write the Old Church Slavonic language. Along with his brother Methodius, he played a crucial role in spreading Christianity among the Slavic peoples. Cyril's work laid the foundation for the development of Slavic literacy and culture. His contributions are celebrated in various Slavic countries, where he is honored as a patron saint. The feast day of Saint Cyril is observed on May 11 in many Eastern Orthodox traditions.