Sir Thomas Duffus Hardy (22 May 1804 – 15 June 1878) was an English archivist and antiquary, who served as Deputy Keeper of the Public Record Office from 1861 to 1878.
As the head of his department he did much to render the records already in the custody of the Master of the Rolls accessible to the public, and muniments of three palatinates: Durham, Lancaster, and Cheshire were brought up to London and thrown open to inspection during his tenure.
[1] After his appointment as Deputy Keeper of the Record Office in 1861 Hardy edited, for the Rolls Series, A Descriptive Catalogue of MSS relating to the History of Great Britain and Ireland (1862–71), the Registrum Palatinum Dunelmense (1873–1878), and a Syllabus in English of Rymer's Foedera (1869); and he also commenced for the same series Lestorie des Engles solum Geffrei Gaimar.
Besides these works he made reports on the documents preserved at Venice relating to English history, and on the collection of papers at the Bodleian Library.
He wrote Syllabus in English of Documents in Rymer's Foedera (3 vols., 1869–1885), and gave an account of the history of the public records from 1837 to 1851 in his Memoirs of the Life of Henry, Lord Langdale (1852).