Diane de Poitiers
Diane de Poitiers was a French noblewoman and a prominent courtier at the courts of king Francis I and his son, King Henry II of France. She became notorious as King Henrys favourite. Because of this, she wielded much influence and power at the French Court, which continued until Henry was mortally wounded in a tournament accident. It was during this tournament that his lance wore her favour rather than his wifes.
She was born the daughter of Jean de Poitiers, Seigneur de Saint Vallier and Jeanne de Batarnay. When still a girl, she was briefly in the retinue of Anne de Beaujeu, eldest sister of King Charles VIII, a capable and highly intelligent woman who held the regency of France during his minority.
Source: Wikipedia