The thesis focuses on the politicisation of myth in the early twentieth century. The notion of myth appears massively in political language at the turn of the century, starting with Romanticism, and is then embraced by the Fascist regimes in Italy and Germany: according to the propaganda, the issue is how to incarnate the myth of the nation, of the “race”, or of the “Third Reich” in social life. Far from being an illusion or a fable, as during the Enlightenment, the myth is now a political reality. The politicisation of the notion of myth coincided with what could be considered a mythisation of politics under fascism, i.e. the setting up of mass gatherings in the form of liturgies, the use of symbols and rites, and the heroisation of the leader. The use of myth as a means to arouse the enthusiasm of the masses, first theorised by Georges Sorel in 1906, thus seems to be the essential element of a new form of politics.Hitherto attributed to the “others”, the so-called “primitives”, and representing the opposite of modern thinking, the myth now expresses, right at a time when the masses are acquiring unprecedented political importance, the imaginary and affective dimension of collective action. At the same time, it is placed at the heart of the fascist ideology. By tracing the history of the notion of myth, the aim of the present work is to reveal this ambivalence, from its emergence to the philosophical critique developed by several authors - from Ernst Bloch to Max Horkheimer and Theodor W. Adorno, or Ernst Cassirer - who seek to understand the mechanisms behind the totalitarian domination over the masses through the use of myth. Based on what Furio Jesi calls the “mythological machine”, I show how myth tends to be hypostasised as a force acting on the “masses”, who then replace the so-called “primitives”. The critique of myth is therefore necessary to understand its role in contemporary history, without at the same time succumbing to its fascination.