Pope Saint Gregory I or Gregory the Great (called the Dialogist in Eastern Orthodoxy) (c. 540 – March 12, 604) was pope of the Catholic Church from September 3, 590 until his death.

He was born to a patrician Roman family (father, Gordianus, and mother, Silvia) and pursued a secular political career which climaxed in the position of Urban Prefect before he entered a monastery. About fifteen years later, he became pope.

Gregory's chief acts as Pope include his role in the schism of the Three Chapters, and sending Augustine of Canterbury to convert the Anglo-Saxons in Britain. He is also known in the East as a tireless worker for communication and understanding between East and West. He is also credited with increasing the power of the papacy. Before his pontificate, the Pope was regarded as the foremost among other high-ranking ecclesiasts, but without any jurisdiction outside his own diocese.

Works of Gregory I:

• Sermons (40 on the Gospels are recognized as authentic, 22 on Ezekiel, 2 on the Song of Songs)
• Dialogues on the life of Saint Benedict
• Commentary on Job, frequently known even in English-language histories by its Latin title, Moralia in Job
• The Rule for Pastors
• Some 850 letters have survived from his Papal Register of letters. This collection serves as an invaluable primary source for these years.
• In the Eastern Orthodox Church, Gregory is credited with devising the Liturgy of Presanctified Gifts . It is celebrated on certain nights during Great Lent in the Eastern Orthodox Church.

The Gregorian Chant, a religious musical style of the Middle Ages, is named for Pope Gregory. Although he is not known to have written any chants himself—the majority of chants written during this time were published anonymously—his influence in the Church caused the style to be named after him.