Louis Demaison (5 November 1852 – 5 May 1937) was a 19th–20th-century French historiographer, archaeologist, and with Henri Jadart, one of the most significant contributors to the nineteenth/twentieth history of the Marne department.
He began his studies in law and after obtaining his license he followed the courses of Gabriel Monod, Gaston Paris and Darmester at the École pratique des hautes études.
An historian graduated from the École Nationale des Chartes in 1876 as palaeographer archivist, he led a parallel administrative career and a career in research with numerous publications alone or with others, including Henry Jadart and Charles Feodor Givelet.
He was a member of numerous scientific societies and academies both national and local, including the Académie des Inscriptions et Belles-Lettres and the Société française d'archéologie [fr], of which he became inspector in 1903.
At its foundation in 1879, he was appointed by the Ministry of Education, a member of the Archaeological Commission responsible for ensuring conservation in France of the "monuments de l'art et de l'histoire" with Henri Jadart and Charles Givelet.