Mollie Greenhalgh Hardwick (7 March 1916 – 13 December 2003) was an English author who was best known for writing books that accompanied the TV series Upstairs, Downstairs.
As well as writing many Upstairs, Downstairs, Thomas & Sarah and The Duchess of Duke Street novels, she was also the creator of the Doran Fairweather novels and wrote three Juliet Bravo books. Hardwick also wrote many books and plays based around the Sherlock Holmes novels. She married fellow author Michael Hardwick (1924-91) in 1961.