Grigori Yakovlevich Perelman is a Russian mathematician who has made landmark contributions to Riemannian geometry and geometric topology.
In 1994, Perelman proved the soul conjecture. In 2003, he proved Thurston's geometrization conjecture. This consequently solved in the affirmative the Poincar' conjecture, posed in 1904, which before its solution was viewed as one of the most important and difficult open problems in topology.
Birthday: June 13, 1966