In the thirteenth and fourteenth centuries, the Cathar religion was eradicated by a military crusade and by the methods of the Inquisition. From the first moments of the crusade against the Albigensians, a literature has emerged in the two enemy camps. Over the centuries, with historical distancing, the Cathars, who were called “Albigensians” for a long time, gradually became a myth. This myth first developed among historians and theologians, then it entered the literary field, especially in the nineteenth century, then especially in the twentieth century when it experienced a real explosion. The subject of this thesis is the complete study of the literature on the subject from the time of the Crusade to the present day: Tome I, La Chair et la Cendre (La croisade-1789), Tome II, Le péché Romantique (1789- 1870); Volume III, Le Soupir du Phénix (1870-1914); Volume IV, L'Idole Bicéphale (1870-2003).