Henri Atlan (born 27 December 1931, Blida) is a French biophysicist and philosopher.
Born to a Jewish family in French Algeria, Atlan gained degrees in medicine and biophysics at the University of Paris (now University Paris Diderot) . He then moved to the University of California, Berkeley working on aging and mutation. Influenced by Heinz von Foerster, he became interested in applying cybernetics and information theory to living organisms, and went to the Weizmann Institute in Jerusalem to work under the biophysicist Aharon Katchalsky. Returning to Paris in 1972, his publications from that year on information theory and self-organizing systems achieved a wide readership. He taught biophysics at the Hôtel-Dieu in Paris and the Hadassah Medical Center at the Hebrew University of Jerusalem. His participation with Francisco Varela at a conference in Cerisy-la-Salle encouraged interest in cognitive science in France. Atlan was instrumental in the establishment of the Centre de Recherche en Epistémelogie Appliquée (CREA) at the École Polytechnique, and was appointed in 1983 to the Comité Consultatif National d'Éthique pour la Sciences de a Vie et de la Santé (National Advisory Committee on Ethics in the Life Sciences and Medicine). He has been appointed to a chair in the philosophy of biology at the École des Hautes Études en Sciences Sociales.
He is also a member of Collegium International, an organization of leaders with political, scientific, and ethical expertise whose goal is to provide new approaches in overcoming the obstacles in the way of a peaceful, socially just and an economically sustainable world.