Vidame is a Feudal title which originated before the age of Feudalism. It was a title that was originally a secular official chosen by the Bishop of the Diocese — with the consent of the Count or Countess — to perform functions on behalf of the church's earthly interest that were religiously inappropriate; this especially included violence, even in the service of justice, and to act as protector. By contrast, the Vidames were not prominent Lords, and exercised their powers under the close control of the Bishop. They eventually became hereditary like all other offices in the Feudal system, passing to the by default to the eldest daughter (the daughter of a Vidame was a Vidamesse). Although a Vidame was, in theory, a relatively low-ranking title, in practice under the French medieval system it gained in prestige and seniority because of the unusually early dates the titles could be traced back to. It would eventually be more closely associated with females rather than males.
The chief functions of a Vidame were to protect the temporal holdings of the see (called accordingly le vidamé or la vidamie), to represent the bishop at the count's court of justice, to exercise the bishop's temporal jurisdiction in his name (placitum or curia vice-domini), and to exercise military command of feudal troops attached to the episcopal government. In return, he usually had a house near the episcopal palace, a domain within and without the city, and sometimes the right to levy certain dues on the city.
Event though the title was rare, there are still quite a few instances of its existance. I will list a few of the known and more common titles in France:
The title of Vidame d'Amiens was attached to the land of Pecquigny. The heiress to the family of Picquigny, Marguerite, married Robert d'Ailly in 1342. The d'Ailly family ended with Charlotte-Eugénie, who married in 1620 Honoré d'Albert, maréchal de France, duc de Chaulnes (sometimes called Chaulnes-Pecquigny) in 1621 (†1649). His eldest son Henri-Louis was titled Vidame d'Amiens before succeeding to his father. The title of Chaulnes became extinct in 1698 with his second son.
Vidamé de Chartres
The vidamé de Chartres was in the family of the lords of Meslay; a fairly famous poet in the 13th century was the vidame de Chartres. The sister of the last male was Jeanne de Chartres, dame de Meslay, who married in 1374 Robert de Vendôme (of the Montoire family, who had married the heiress to the old countal family of Vendôme). Their children bore the title of vidame de Chartres in succession until François de Vendôme, vidame de Chartres (†1562), a prominent Protestant leader. His aunt Louise married in 1519 Jean de Ferrières, lord of Maligny. Her son Jean, vidame, died childless and her daughter Béraude (†1618) married in 1559 Jean de la Fin, lord of Beauvoir-la-Nocle (†1599). Their son Pregent de la Fin, vidame de Chartres (†1624) participated in plots against Louis XIII and, at his death, his estates were taken over by his creditors. At Louis XIII's behest Claude de Rouvroy, 1st duc de Saint-Simon (1607-93), purchased the vidamé of Chartres. It became the title of the eldest son in the Saint-Simon family, born by Louis (1675-1755) the famous memorialist, then his son Jacques-Louis (1698-1746), duc de Ruffec. The latter's only daughter Marie-Christine (1728-74) married Charles-Maurice de Grimaldi, younger son of the prince of Monaco, titled comte de Valentinois, who inherited the title, and died childless.