Pierre Jean-Baptiste Legrand d'Aussy (3 June 1737 - 6 December 1800) was a French antiquarian and historian, who introduced the terms menhir and dolmen, both taken from the Breton language, into antiquarian terminology.
A result was the Voyage dans la haute et basse Auvergne (Paris, 1788).
With the Revolution, in 1795 Legrand was named conservator of French manuscripts in the Bibliothèque nationale.
He took up once again an earlier project of writing a complete history of French poetry.
Having translated the Old French into modern French and published a large number of analyses of old French poets in the Notices des Manuscrits de la Bibliothèque du Roi, he enlarged his frame of reference, but have completed only some parts of his great work, when he died suddenly, in Paris, 6 December 1800.
Legrand was a member of the Institut de France.