Charles Ehresmann (1905-1979) was a French mathematician who worked on differential topology and category theory. He is known for work on the topology of Lie groups, the jet concept (see jet bundle), and his seminar on category theory. He attended the École Normale Supérieure in Paris before performing a years military service.
In 1957 he founded the mathematical journal Cahiers de Topologie et Géometrie Différentielle Categoriques.
Dieudonné describes Ehresmann's personality as "... distinguished by forthrightness, simplicity, and total absence of conceit or careerism. As a teacher he was outstanding, not so much for the brilliance of his lectures as for the inspiration and tireless guidance he generously gave to his research students ... "
- O'Connor, John J., and Edmund F. Robertson. "Charles Ehresmann". MacTutor History of Mathematics archive.