Jean-Baptiste Regnault was a French painter.
Regnault was born in Paris, and began life at sea in a merchant vessel. At the age of fifteen his talent attracted attention, and he was sent to Italy by M. de Monval under the care of Bardin. After his return to Paris in 1776, Regnault won the Grand Prix for his painting Alexandre and Diogène, and in 1783 he was elected to the French Académie des Beaux-Arts. His diploma picture, The Education of Achilles by Chiron the Centaur, is now in the Louvre, as also are his Trois Grâces, Le Déluge, Descente de croix (Christ taken down from the Cross, originally executed for the royal chapel at Fontainebleau) and Socrate arrachant Alcibiade du sein de la Volupté.

His L'origine de la peinture and L'origine de la sculpture, ou Pygmalion amoureux de sa statue are now at the Palace of Versailles.

Besides various small pictures and allegorical subjects, Regnault was also the author of many large historical paintings; and his school, which reckoned amongst its chief attendants Guérin, Crepin, Lafitte, Blondel, Robert Lefèvre, Henriette Lorimier and Alexandre Menjaud, was for a long while the rival in influence of that of David.

Besides Merry-Joseph Blondel, Pierre-Narcisse Guérin, Robert Lefèvre, and Henriette Lorimier, Jean-Baptiste Regnault's students include: Godefroy Engelmann, Louis Hersent, Charles Paul Landon, Hippolyte Lecomte, Jacques Réattu, Jean-Hilaire Belloc.

Jean-Baptiste Regnault was married first to Sophie Meyer, then Sophie Félicité Beaucourt.

He died in Paris. He is buried in Père-Lachaise Cemetery.