Louis Sigismond Isaac Halphen (4 February 1880, Paris – 7 October 1950, Paris) was a French medieval specialist and the author of many important books over a long career. He was noteworthy as the editor of a modern edition of the famous classic Einhard's "Vie de Charlemagne" (Paris, 1947), He was also known as being one of the general editors of the monumental series Peuples et civilisations.

Louis Halphen was born in Paris to mathematician Georges Henri Halphen. He married Germaine Weill, the daughter of Mathieu Weill, in 1910, with whom he had two children: Étienne and Geneviève.^[1]