Bill Thurston! He did amazing topology - hyperbolic knot compliments, Foliations, eversion of the sphere, geometrization conjecture... A brilliant man. I had

Bill Thurston! He did amazing topology - hyperbolic knot compliments, Foliations, eversion of the sphere, geometrization conjecture... A brilliant man. I had the honor of meeting him several times here in Berkeley; he encouraged me to make Klein bottles and other topological shapes.