Ganelon
Ganelon (US: /ˌɡænəˈloʊn/, French: [ɡan(ə)lɔ̃]) is the fictional knight who betrayed Charlemagne's army to the Saracens in the 11th century Matter of France, leading to the 778 Battle of Roncevaux Pass. He is based upon the historical Wenilo, the archbishop of Sens who betrayed King Charles the Bald in 858, though it has been suggested that his name is derived from the Italian word inganno, meaning fraud or deception.