Prince étranger (English: "foreign prince") was a high, though somewhat ambiguous, rank at the French royal court of the ancien régime.
In medieval Europe, a nobleman bore the title of prince as an indication of sovereignty, either actual or potential. Aside from those who were or claimed to be monarchs, it belonged to those who were in line to succeed to a royal or independent throne. France had several categories of prince in the post-medieval era. They frequently quarrelled, and sometimes sued each other and members of the nobility, over precedence and .
The foreign princes ranked in France above "titular princes" (princes de titre, holders of a legal but foreign title of prince which carried no right of succession to any sovereign realm), and above most titled nobles, including the highest among these, dukes. They ranked below acknowledged members of the House of Capet, France's ruling dynasty since the tenth century. Included in that royal category (in ascending order) were:
This hierarchy in France evolved slowly at the king's court, barely taking into account any more exalted status a foreign prince might enjoy in his own dynasty's realm. It was not clear, outside the halls of the Parlement of Paris, whether foreign princes ranked above, below, or with the holder of a French peerage.
Deposed rulers and their consorts (e.g. King James II of England, Queen Christina of Sweden, Duchess Suzanne-Henriette of Mantua, etc.), ranked above the foreign princes, and were usually accorded full courtesies at court, for as long as they remained welcome in France.