Cyrillus is a name that can refer to various historical and cultural figures, but it is most commonly associated with Saint Cyril, a Christian missionary and scholar from the 9th century. He is known for creating the Glagolitic alphabet, which was the first alphabet used to transcribe the Old Church Slavonic language. Along with his brother, Methodius, he played a significant role in spreading Christianity among the Slavic peoples. Saint Cyril is celebrated for his contributions to literacy and education in Eastern Europe. His work laid the foundation for the development of the Cyrillic alphabet, which is still used today in many Slavic languages, including Russian and Bulgarian. His legacy continues to influence cultural and religious practices in these regions.