Which mathematician refused the Fields Medal?

Grigori Perelman refused the Fields Medal, the highest honor in mathematics, because he felt disillusioned with the mathematical community and perceived the award process as tainted. Perelman's groundbreaking work proved the Poincaré Conjecture, one of the most significant problems in topology. However, he had already turned down other prestigious awards, and when the Fields Medal was offered in 2006, he declined it. Perelman expressed his dissatisfaction with the lack of recognition given to his collaborators and voiced criticisms against the broader mathematical community. These frustrations, combined with his desire for a simple and solitary life, led to his refusal of the prestigious honor.