Diane de Poitiers (3 September 1499 – 25 April 1566) was a French noblewoman and a prominent courtier at the courts of kings Francis I and his son, Henry II. She became notorious as the latter's favourite. It was in this capacity that she wielded much influence and power at the French Court, which continued until Henry was mortally wounded in a tournament accident, during which his lance wore her favour (ribbon) rather than his wife's.

She was born the daughter of Jean de Poitiers, Seigneur de Saint Vallier, and Jeanne de Batarnay in the Chateau de Saint-Vallier. 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.

Diane was educated according to the principles of Renaissance humanism which was popular at the time - music, hunting, manners, the art of conversation and dancing. She learned how to read Latin and Greek and became a keen hunter and sportswoman, remaining in good physical condition well into middle age.

At the age of 15, she married Louis de Breze, Seigneur d'Anet, who was 39 years her senior. He was a grandson of king Charles VII who served as a courtier of king Francis I. She bore him two daughters, Frnancoise de Breze (1518 - 1574) and Louise de Breze (1521 - 1577).

In 1524 her father was accused of treason as an accomplice of the rebellious Connetable de Bourbon. His head was already on the execution block when his life was spared by Francsi I.