Adolphe Étienne Auguste Moreau-Nélaton (2 December 1859 – 25 April 1927) was a French painter, art collector and art historian. His large collection is today held in its entirety by French national museums.

Moreau-Nélaton was born and died in Paris. His family's art collecting began with his grandfather Adolphe Moreau (1800–1859). As a stockbroker he possessed ample capital with which to buy the work of artists with whom he was personally acquainted, including Eugène Delacroix and Alexandre-Gabriel Decamps. Moreau-Nélaton's father, who was also named Adolphe Moreau (1827–1882), was a high government official and led the railroad company Chemins de fer de l'Est. In 1856 he married the ceramic artist Camille Nélaton (1840–1897), with whom he further expanded the family's collection.

After an 1882 visit to the École Normale Supérieure, Moreau-Nélaton decided to become a painter. He began his artistic education by studying with the artists Henri-Joseph Harpignies and Albert Maignan, who were friends of the family. In 1885 he exhibited for the first time in the Salon de Paris. His painting style was influenced by Édouard Manet and Berthe Morisot. Domestic family scenes were his primary subject matter, but he also painted several landscapes. Some of his works are now in the collection of the Musée d'Orsay.

• Children at the Piano
• La place de Fère-en-Tardenois
• Scène d'intérieur
• L'enfant au livre
• Étretat

• Posters published in Les Maîtres de l'Affiche
• Poster 58
• Poster 118
• Poster 162
• Poster 178
• Poster 198

Despite his artistic output, Moreau-Nélaton was perhaps more important as a collector and patron. He first expanded his family's collection to include paintings by Jean-Baptiste-Camille Corot, Narcisse Virgilio Díaz de la Peña, Constant Troyon, Théodore Géricault, Thomas Couture, Honoré Daumier and Charles-François Daubigny. Works by Henri Fantin-Latour followed, including Hommage à Delacroix. Moreau-Nélaton also belonged to the group of subscribers who secured and purchased Manet's Olympia for the nation of France in 1890. His collection of impressionist painting was especially impressive, with 10 works by Claude Monet alone, including the well-known Poppyfield at Argenteuil. It also included 7 works by Alfred Sisley, 2 works by Camille Pissarro, and 5 works by Édouard Manet, including The Luncheon on the Grass.

Other painters represented in the collection included Pierre Puvis de Chavannes, Pierre-Paul Prud'hon, Johan Barthold Jongkind, Jean-Louis Forain and Eugène Carrière. Most of the paintings were donated to the Louvre in 1906, and today are displayed either there or in the Musée d'Orsay. Further sections of it were willed to state museums after his death. Among these were sculptures by Alfred Charles Lenoir, Aristide Maillol and Aimé Jules Dalou. In addition to all of this he also willed over 3,000 drawings and prints by various artists to the Louvre.