Ogier the Dane (French: Ogier le Danois, Ogier de Danemarche; Danish: Holger Danske) is a legendary paladin of Charlemagne who appears in many Old French chansons de geste. In particular, he features as the protagonist in La Chevalerie Ogier (c. 1220), which belongs to the Geste de Doon de Mayence ("cycle of the rebellious vassals"; Doon is Ogier's grandfather). https://en.wikipedia.org/wiki/Ogier_the_Dane