Châtelain (Med. Lat. castellanus, from castellum, a castle) was originally merely the French equivalent of the English castellan, i.e. the commander of a castle.
With the growth of the feudal system, however, the title gained in France a special significance which it never acquired in England, as implying the jurisdiction of which the castle became the centre. The châtelain was originally, in Carolingian times, an official of the count; with the development of feudalism the office became a fief, and so ultimately hereditary. In this as in other respects the châtelain was the equivalent of the viscount; sometimes the two titles were combined, but more usually in those provinces where there were châtelains there were no viscounts, and vice versa.
The title châtelain continued also to be applied to the inferior officer, or concierge châtelain, who was merely a castellan in the English sense. The power and status of châtelains necessarily varied greatly at different periods and places. Usually their rank in the feudal hierarchy was equivalent to that of the simple sire (dominus), between the baron and the chevalier; but occasionally they were great nobles with an extensive jurisdiction, as in the Low Countries (see Burgrave).