Saint Gregory the Great (c. 540–604) was pope from 590 until his death, and one of the most influential figures in the formation of the medieval Western Church. His pontificate marked a decisive moment in the transformation of the Roman Church from a late-antique institution into a distinctly medieval papacy, combining pastoral care, missionary ambition, liturgical reform, and practical governance. He was later proclaimed a Doctor of the Church, reflecting the enduring authority of his theological and pastoral writings.