Lady Mary Christina Holborow DCVO (née Stopford; 19 September 1936 – 9 June 2017) was a British magistrate who was Lord Lieutenant of Cornwall.

On retirement as a magistrate (justice of the peace) she became the Lord Lieutenant of Cornwall and then a trustee of Cornwall Rural Community Council, the South West Lakes Trust, the National Maritime Museum, Falmouth and the TR14ers Community Dance Team Team based in Camborne.

Lady Mary served as Commissioner for St John Ambulance Cornwall from 1982 until 1987, being made DStJ (1987).

Her work and chairmanship of the Cornwall chapter of Macmillan Cancer Relief was longstanding and especially relevant to her personal commitment to the hospice movement and health services within the county.

Lady Mary was appointed Dame Commander of the Royal Victorian Order (DCVO) in the 2010 Birthday Honours.