Isidore-Alexandre-Augustin Pils (1815–1875) was a French academic painter of religious and military subjects.

Pils was born in Paris as the son of a soldier François Pils. At the age of twelve, he studied with Guillaume Guillon-Lethière for four years.

In 1831 he became a student at the École des Beaux-Arts^[1] and studied under François-Édouard Picot.^[2] He competed for the Prix de Rome, which he won in 1838 for a history painting, St. Peter Healing a Lame Man at the Door of the Temple.^[3] Although in poor health, Pils then spent the customary three years at the French Academy in Rome at the Villa Medici, which then had Jean Auguste Dominique Ingres as its director. While in Italy he visited Naples, Venice, and Florence.

Pils's earlier paintings have religious themes.^[1] In 1849 he completed his most famous work, Rouget de L'Isle Singing La Marseillaise, which now resides at the Musée historique de Strasbourg. After experiences travelling with French troops through the Crimea, his themes took on military and nationalistic subjects. He later produced many military scenes during the siege of Paris during the Franco-Prussian War of 1870.