Mary Alice Cavendish, Duchess of Devonshire, was a British courtier who served as Mistress of the Robes to Queen Elizabeth II from 1953 to 1967. She was the granddaughter of Prime Minister Robert Gascoyne-Cecil, 3rd Marquess of Salisbury.

The mistress of the robes was the senior lady in the Royal Household of the United Kingdom, who would, by appointment, attend on the Queen. Queens dowager retained their own mistresses of the robes. In the 18th century Princesses of Wales had one, too.