Nominoe or Nomenoe (French: Nominoë; Breton: Nevenoe; d. 7 March 851) was the first Duke of Brittany from 846 to his death. He is the Breton pater patriae and to Breton nationalists he is known as Tad ar Vro ("father of the country").
He was the second son of Count Erispoë I of Poher, King of the Browaroch (775 - 812), and younger brother of Count Riwallon or Rivallon III of Poher (? - 857).
After a general rebellion which had enveloped the entire Carolingian Empire was put down, a general assembly was held at Ingelheim in May 831. It was probably there that the emperor Louis the Pious appointed Nominoe, a Breton, to rule the Bretons (which corresponded to "almost all" of Brittany).Regino of Prüm in his famous Chronicon writes, inaccurately for the year 837, that:
Murmanus rex Brittonum moritur et Numenoio apud Ingelheim ab imperator ducatus ipsius gentis traditur.
Morman, king of the Bretons, died and Numenoi [Nominoe] was created duke of that same people by the emperor at Ingelheim.
Nominoe was a staunch ally of Louis the Pious until the emperor's death in 840. He supported Louis in the several civil wars of the 830s and he supported the monastery of Redon Abbey, even ordering the monks to pray for Louis in light of the emperor's "strife". Nominoe's power base was in the Vannetais and two charters refer to him as Count of Vannes, though it is unknown when that title was held, be it as early as 819 or as late as 834. Nominoe may not have possessed any land outside Vannes and his ability to gather revenue in Breton-speaking territories was probably no greater than any other aristocrat of those regions. His chief source of income after he broke with his overlord was plunder from raids into Frankish territory and from the despoliation of churches. He did have the political authority to exact payment (wergild) in the form of land from a man who had murdered his follower Catworet.