Institut des Hautes Études Scientifiques · CC BY 3.0

A mathematician who reshaped geometric group theory and metric geometry, developing techniques — Gromov-Hausdorff convergence, hyperbolic groups, pseudoholomorphic curves — that other mathematicians now treat as standard tools. He holds a permanent position at the Institut des Hautes Études Scientifiques in France and a professorship at New York University, and won the Abel Prize in 2009 for what the citation called his "revolutionary contributions to geometry."