Catherine-Henriette Bellier, baroness de Beauvais (Poitou, 1614 – 7 June 1689 in Arrou), was a French courtier, the first mistress of king Louis XIV of France.
She was the daughter of Martin Bellier, married baron Pierre de Beauvais and became lady in waiting to the French queen Anne of Austria. She is described as intelligent, plotting and a trusted companion of the queen dowager regent. Despite being desceibed as uggly, she had several love affairs, such as the one with the arch bishop of Sens. Bellier was entrusted by the queen dowager with the task to provide the fourteen year old king with sexual education by seducing him and deprive him of his virginity in 1652. Their sexual relationship lasted for two years, after which she was awarded by the queen dowager with an estate and a pension.
She constructed the Hotel de Beauvais in Marais in Paris.