Le présent article entend lever le voile sur la carrière d’un personnage méconnu de l’historiographie, grec d’origine et parvenu en trois décennies à un haut niveau de réussite sociale. Issu d’un milieu grec pérote marchand habitué à graviter entre deux mondes – grec orthodoxe et ottoman musulman –, Démétrios Paléologue a su utiliser ses qualités de marchand et d’intermédiaire pour s’insérer dans le jeu diplomatique du deuxième tiers du xvie siècle méditerranéen. La nouveauté réside dans son attachement au service du roi François Ier, un prince apparemment peu habitué à user des services de ces personnes interlopes. L’analyse montre également que Démétrios ne reste pas en marge du service du roi de France mais profite de celui-ci pour fonder une assise sociale et économique qui s’ancre dans le royaume. Le changement de paradigme qu’incarne Démétrios Paléologue justifie la portée de l’article : plutôt qu’un marchand ou un diplomate de passage, nous avons affaire à un Grec venu d’Orient qui s’implante durablement dans un royaume extra-méditerranéen tout en conservant des liens, notamment marchands, avec le monde méditerranéen. Pour la France du milieu du xvie siècle, le cas est rare mais, plutôt qu’une exception, il faut comprendre la carrière de Démétrios Paléologue comme la partie émergée d’un phénomène plus large de la présence grecque en Europe du nord-ouest qui demande encore à être défriché. The purpose of this article is to explore foreignness as a condition of social climbing in the French 16th century. Demetrios Palaiologos was a Greek interpreter, merchant and officer who served King Francis I of France between 1533 and 1560. His life is still largely ignored by the historiography. Demetrios first acted as a broker between the French and Ottoman diplomacy in the 1530s, serving the French as an intercessor and diplomatic agent. Thanks to these first activities, Demetrios stayed at the king’s service and settled himself in Paris as a curial officer of His Majesty and a Parisian bourgeois by marriage into an influential family, the Vitrys. There, Demetrios was identified alternately as a bourgeois, a merchant, an officer, and, sometimes, as a Greek, but never as a foreigner. This work shows that the classic historiography, which conceptualizes the building of Modern state in Modern Europe as an administrative process of rationalization by the power of the Prince, must be discussed. Indeed, when the French kings wanted to negotiate with the Ottomans, they couldn’t find any interpreter. So Francis I and his successors chose to employ some people who were not really their subjects but were coming from Eastern Mediterranean, being for sale as brokers. These people, like Demetrios Palaiologos, served their masters and themselves. As an interpreter, Demetrios succeeded to serve the king, enter the French Court, and get money. As an officer at the Court, he got influence… and money. As a merchant, he got influence on the Parisian Bourgeoisie... and money. As a rich man, Demetrios Palaiologos had become a man of (soft) power. This case must be understood as the first example of the Greeks’ influence in Northwestern Europe’s societies, which can be associated with the concept of state building. This issue remais rather understudied.