Julian Fellowes, Alexander McCall Smith, Tracy Chevalier, Joanna Trollope and Terry Pratchett are among the authors who have created imaginary biographies to accompany the works.
The gallery has a number of paintings which were purchased in the 19th and 20th centuries in the belief that they represented famous people, only for the identities of the sitters to be disproved or disputed.
A painting known as False Mary, painted in 1570 and once thought to be a portrait of Mary, Queen of Scots, captured the imagination of McCall Smith. He has written a story identifying her as a body double for the Queen.
For further information from the National Portrait Gallery itself, click here.