Alan I (French: Alain; died 907), called the Great,[1] was the Count of Vannes and Duke of Brittany (dux Brittonium) from 876 until his death.
He succeeded his brother Pascweten in Vannes when the latter died, probably in the middle of 876, and contended for leadership of Brittany with Judicael of Poher.
He ruled not only the Breton territories of Léon, Domnonée, Cornouaille, and the Vannetais, but also the Frankish counties of Rennes, Nantes, Coutances, and Avranches, as well as the western parts of Poitou (the so-called pays de Retz) and Anjou.
His strongest opponent was Fulk I of Anjou, who disputed control of the Nantais with him, though Alan seems to have had the upper hand in his lifetime.
A charter datable to between 897 and 900 makes reference to the soul of Karolus on whose behalf Alan had ordered prayers to be said in the monastery of Redon.