The Einstein of Mathematics:
Alexander Grothendieck was born in 1928 in Berlin, Germany, to anarchist parents and became a French citizen after the war. He started in functional analysis but soon focused on algebraic geometry.
Grothendieck developed the theory of schemes to provide a general setting for algebraic varieties. He made major contributions to sheaf theory, homological algebra, and category theory during his time at the IHES.
His multi-volume Éléments de géométrie algébrique set new standards in algebraic geometry. Grothendieck received the Fields Medal in 1966. He eventually left mathematics and lived reclusively in France until his death in 2014.