Mary Capel, Countess of Essex, born Lady Mary Bentinck, was the daughter of William Bentinck, 1st Earl of Portland, a Dutch and English nobleman who became in an early stage the favourite of stadtholder William, Prince of Orange and his wife Anne Villiers.

William Bentinck, 1st Earl of Portland, was a Dutch-born English nobleman who became in an early stage the favourite of William, Prince of Orange, Stadtholder in the Netherlands, and future King of England. He was reportedly steady, sensible, modest and usually moderate. The friendship and cooperation stopped in 1699.