Joseph-Siffred Duplessis[1] (22 September 1725 – 1 April 1802) was a French painter known for the clarity and immediacy of his portraits.

He was born in Carpentras, near Avignon, into a family with an artistic bent and received his first training from his father, a surgeon and talented amateur.

Duplessis returned to Carpentras, spent a brief time in Lyon then arrived about 1752 in Paris, where he was accepted into the Académie de Saint-Luc and exhibited some portraits, which were now his specialty, in 1764, but did not achieve much notice until his exhibition of ten paintings at the Paris salon of 1769, very well received and selected for special notice by Denis Diderot; the Académie de peinture et de sculpture accepted him in the category of portraitist, considered a lesser category at the time.

Afterwards, from 1796, he served as curator at the newly founded museum formed at Versailles, so recently emptied of its furnishings at the Revolutionary sales.

Duplessis would adjust his style to the social condition of his sitter: his portrait of Charles-Claude, comte d'Angiviller, director of the Bâtiments du Roi, is as distant and conventional as his state portrait of Louis XVI in coronation robes (1776),[2] while his realistic and intimate portrait of the opera composer Christoph Willibald Gluck (Kunsthistorisches Museum, Vienna) catches the composer at the keyboard in a moment of inspiration and his penetrating portrait of the sculptor Christophe Gabriel Allegrain (Louvre Museum, illustration) shows him having just laid down his chisel: this was the morceau de reception that gained him admittance to the Académie.