Alain I most commonly refers to Alain I of Albret (1440–1522), the 16th Lord of Albret, however it may also refer to:
Alan I, Viscount of Rohan (1084–1147), also known as Alain de Rohan, was the first viscount of Rohan Alan I, King of Brittany (died 907), also known as Alain, was likely the only king of Brittany to hold the title by grant of an emperor