The Yew Tree Ball () was a masked ball. It was held in the Hall of Mirrors at Versailles on the night of 25-26 February 1745. Fifteen thousand people waited in the Hercules Room for the ball to begin. King Louis XV and several of his gentlemen courtiers attended dressed as topiary yew trees. The ball is notorious for being the venue in which the king made contact with Jeanne-Antoinette Poisson. He had first seen her while hunting at Senart. On 14 September 1745, Poisson was officially presented to the Court as the Marquise de Pompadour. She was the king’s official mistress until her death in 1764. 