(b. 1754, Paris, d. 1837, Paris)
French painter. He was a student of Jean-François-Pierre Peyron in Paris and, thanks to a sponsor, the Marquis de Couberon, followed his master to Rome in 1776. He stayed four years and made the acquaintance of Jacques-Louis David and Pierre Henri de Valenciennes.
On his return to Paris he exhibited at the Salons de la Correspondance of 1781 and 1782. Monsiau was approved (agréé) as an associate of the Académie Royale on 30 June 1787 for Alexander Taming Bucephalus and was received (reçu) only on 3 October 1789, after a previous application had been refused; his morceau de réception was the Death of Agis.
In his best-known painting, Zeuxis choosing among the most beautiful girls of Crotona, shown at the Salon of 1791, Monsiau illustrates an anecdote of the painter Zeuxis, recorded in Pliny's Natural History.
Affected by the hangings in 1792 and 1793 of his two protectors and by the slump in commissions brought about by the Revolution, he turned to book illustration for editions of Ovid, Jean-Jacques Rousseau, Laurence Sterne, Jacques Delille and Salomon Gessner.
After the restoration in 1814 he returned to Neo-classical subject matter, producing fewer modern historical or literary subjects. He also painted a few portraits and genre scenes, showing for the last time in public at the Salon of 1833, four years before his death.