Augustin Blondel de Gagny (French pronunciation: ​[oɡystɛ̃ blɔ̃dɛl də ɡaɲi]; March 1695 – 9 July 1776) was a French connoisseur of the arts and a collector whose series of Paris auction sales, which took place soon after his death were high-water marks of the history of collecting in 18th-century France. Paintings and sculptures that passed through Blondel de Gagny's collection are dispersed in many of the world's great museums. The prints from his collection are less easily traced.