Saint Mellitus (d. April 24, 624), was Bishop of London and third Archbishop of Canterbury. Mellitus was the leader of the second group of missionaries sent by Pope Gregory I from Rome to join Augustine at Canterbury in 601.

Bede describes him as being of noble birth (Hist. Eccl., II, vii) and Pope Gregory describes him as an abbot (Letters, xi, 54, 59). He may have been abbot of the monastery of St. Andrew on the Celian Hill, founded by Gregory, to which both Gregory belonged before he became pope and Augustine belonged before he was sent to Kent.