Jacut was a 5th-century Cornish Saint who worked in North-west France.
His father was Fragan, a prince of Dumnonia, and his mother Gwen Teirbron. The young family had fled to Britany to avoid the plague raging in Cornwall at that time, and so grew up in Ploufragan near Saint-Brieuc with his brothers, Winwaloe and Wethenoc and a sister, Creirwy. He was educated by Budoc of Dol on the Île Lavret near Paimpol, and as an adult he founded churches in Brittany.
Today he is memorialised in the towns of Saint-Jacut-les-Pins, Saint-Jacut-du-Mené, Saint-Jacut-de-la-Mer and the Abbey of Saint-Jacut in that town.