The Musée Cognacq-Jay is a museum located in the Hôtel Donon in the 3rd arrondissement of Paris.

Marie-Louise Jaÿ was a French businesswoman who started work as a shop girl. With her husband Ernest Cognacq she created the La Samaritaine store in Paris, which grew into a chain of large department stores. Innovations included good lighting, clearly marked fixed prices, and allowing customers to pick out their own clothes and try them on before buying. The couple were active in philanthropic work, and gave out bonuses for large families during the population crisis that followed World War I (1914–18).