Domangart I (Scottish Gaelic: Domangart mac Fergusa) was king of Dál Riata from about 501 until 507, following the death of his father, Fergus Mór Mac Earca. He may have joint ruled with his uncle, Aeneas.

Domangart married Feldelm Foltchain, daughter of Brion son of Eochaid Mugmedon, a half-brother to the High King of Ireland Niall of the Nine Hostages. He has at least two sons: Comgall and Gabhran, both of whom became kings in succession. The Tripartite Life of St. Patrick states that he was present at the death of the saint, circa 493. Domangart died around 507 and was succeeded by Comgall.