Mary Stewart, Duchess of Richmond and Duchess of Lennox (1622–1685), formerly Lady Mary Villiers, was the daughter of the George Villiers, 1st Duke of Buckingham and Katherine Manners, Baroness de Ros.

They had two children: Sometime before 1664, Mary married Colonel Thomas Howard (d. 1678): he was a younger brother of Charles Howard, 1st Earl of Carlisle, and is chiefly remembered for his duel in 1662 with Henry Jermyn, 1st Baron Dover.

In October 1670 the duchess, with the queen, and her friend the Duchess of Buckingham decided to go to a fair near Audley End disguised as country women for a "merry frolic", dressed in red petticoats and waistcoats.

The costumes were outlandish rather than convincing, and they began to draw a crowd, when they tried to buy stockings and gloves their speech was also conspicuous.

[2] Mary is the subject of several paintings by Anthony van Dyck as well as a portrait with her children by John Michael Wright.