In Chrétien’s Yvain and its adaptations, the alias given to Yvain after he rescued a lion from a serpent. The lion became Yvain’s friend and guardian and refused to leave his side.
In the Prose Lancelot, this designation is given to Yvain after Sir Lionel of Gaul gives him the skin of the Crowned Lion of Libya.
Sources
Yvain, or Le Chevalier au Lion | Chrétien de Troyes, late 12th century
Lancelot do Lac | 1215-1220
Owain | 13th century
Ivens Saga | 13th century