French historian noted for his studies of the French Middle Ages.

After a brief career in administrative services and journalism, Giry devoted himself to scholarship. His first major work was Histoire de la ville de Saint-Omer et de ses institutions jusqu'au XIV^e siècle (1877). The type of research involved in this work led him to similar studies on a larger scale: Les Établissements de Rouen, 2 vol. (1883–85); Documents sur les relations de la royauté avec les villes de France de 1180 à 1314 (1885); and Études sur les origines de la commune de Saint-Quentin (1887). His Manuel de diplomatique (1894), a guide to the study of ancient documents and charts, formed the basis for later studies of the documentary history of the French Middle Ages, particularly the Carolingian period, written by Giry and his students. He also wrote articles on medieval sciences, contributed to historical encyclopaedias, and edited collections of medieval texts.