Jean-François Thiriart (22 March 1922, Brussels – 23 November 1992), often known as Jean Thiriart, was a Belgian far-right political theorist. Coming from a left-wing background, during the Second World War he was a collaborator with the Nazi Third Reich, as a result of which he served a prison sentence. In the 1960s, he founded and directed the transnational Jeune Europe (Young Europe) movement. He was the theorist of European national communism, a synthesis of revolutionary nationalism and Pan-European nationalism, a form of revolutionary nationalism transposed up to the scale of Europe as a unitary state. Coming from a left-wing family, Thiriart was initially a member of some Socialist and antifascist movements. He switched to far-right politics and joined the extremist Fichte Bund. In 1940, he was associated with Les Amis du grand Reich Allemand, a group composed of former far-left activists which supported collaborationism with the Third Reich. Thiriart himself served in the Waffen SS and later served time in prison for his collaboration. Upon his release, he set up in business as an optometrist. Thiriart returned to the political scene in the 1960s, after in 1960 Belgium had granted independence to the Belgian Congo, which became the Republic of the Congo (Léopoldville), setting off the Congo Crisis. Due to his strong opposition to this development, Thiriart became associated with the Mouvement d'Action Civique (MAC), although he also became interested in a more international vision. Establishing links with French groups similarly opposed to decolonization, Thiriart eventually became a European nationalist, convinced of the need for a united Europe. As a result, he formed Jeune Europe, a movement aiming to reach out across Europe, soon founding branches in Italy, Spain, and France. In Belgium, he continued to co-operate with MAC, which enjoyed close ties to Jeune Europe.