Marie-Sophie Germain (Paris 1776 – 1831) was a self-taught mathematician, who made important contributions to number theory and elasticity theory. One of her most important works was Germain’s Theorem, an important step in proving Fermat’s last theorem. Being a woman, she could not develop a mathematical career in any academic institution, for this reason she worked independently throughout her life. She autographed her researches and studies as “M. Leblanc” to hide her identity.