Liutwin was a Frankish nobleman of the Carolingian kindred — paternal kinsman of Pippin of Herstal, the powerful mayor of the palace whose son Charles Martel and grandson Pippin the Short founded the Carolingian dynasty.
Around 690, after the death of his wife, he founded the great Abbey of Mettlach on the Saar river — endowing it with his ancestral lands and entering it as a monk. His foundation became the principal Carolingian-period monastic centre of the Saar valley.
Around 705 he was consecrated Archbishop of Trier — and shortly afterward also Archbishop of Reims and Bishop of Laon, holding the three sees simultaneously in a foundational pluralist pattern that would become typical of the Carolingian-aristocratic episcopate. His three-fold tenure was the foundation of the medieval Trier-Reims relationship.
He died around 715 at Reims and was buried at his own foundation of Mettlach. His son Milo succeeded him as Archbishop of Trier and Reims — the most blatant of the early-Carolingian episcopal dynasties, eventually censured by St. Boniface as scandalous.