Doon de Mayence was a fictional hero of the Old French chansons de geste, who gives his name to the third cycle of the Charlemagne romances dealing with the feudal revolts. There is no single unifying theme in the geste of Doon de Mayence. The rebellious barons are connected by the poets with Doon by fictitious genealogical ties and all are represented as opposing Charlemagne, although their adventures—insofar as they possess a historical basis—generally occur before (or after) his reign.