Poitiers

The House of Poitiers, known as Poitiers-Valentinois, was a twelfth-century feudal line of the Valentinois around Valence on the Rhone, unrelated to the greater counts of Poitiers in Poitou. Guillaume de Poitiers was recognised as count of Valentinois by the count of Toulouse in 1163 and by Emperor Frederick Barbarossa in 1178, his son Aymar II receiving the county of Diois in 1189; Aymar's marriage extended the house into the Vivarais across the Rhone.

For two and a half centuries the counts held Valentinois and Diois together, until Louis II de Poitiers, dying without legitimate heirs in 1419, bequeathed both counties to the dauphin Charles, the future Charles VII, on condition they remain joined to the Dauphine.

Junior branches carried the name onward: the seigneurs de Saint-Vallier, whose most famous daughter was Diane de Poitiers, mistress of Henry II, ended in the male line in 1547, while the barons of Vadans, settled in Champagne and the Franche-Comte, survived until 1715.