Denis Jean Achille Luchaire (October 24, 1846 - November 14, 1908), French historian, was born in Paris.

In 1879 he became a professor at Bordeaux and in 1889 professor of mediaeval history at the Sorbonne; in 1895 he became a member of the Académie des sciences morales et politiques, where he obtained the Jean Reynaud prize just before his death.

The most important of Achille Luchaire's earlier works is his Histoire des institutions monarchiques de la France sous les premiers Captiens (1883 and again 1891); he also wrote:

• Manuel des institutions françaises: periode des Captiens directs (1892)
• Louis VI. le Gros, annales de sa Vie et de son régne (1890)
• Etude sur les actes de Louis VII. (1885).

His later writings deal mainly with the history of the papacy, and took the form of an elaborate work on Pope Innocent III. This is divided into six parts:

1. Rome et Italie (1904)
2. La Croisade des Albigeois (1905)
3. La Papaute et l'empire (1905)
4. La Question d'Orient (1906)
5. Les royautés vassales du Saint-Siège (1908)
6. Le Concile de Latran et la réforme de l'Eglise (1908)

He wrote two of the earlier volumes of Ernest Lavisse's Histoire de France.