A warrior listed in the Welsh Triads as having one of the “faithless war-bands”. They apparently deserted him before the battle of Camlann and, as a consequence, he was killed there. It is unclear which side he was supporting.
The name comes from an actual person – Alannus Fergannus, the Duke of Brittany from 1084 to 1112, who fought against and then allied with William the Conqueror.
Triads of the Island of Britain | 11th century to 14th century