Grigori Perelman is a Russian mathematician known for his groundbreaking work in geometry and topology. He gained international recognition for solving the Poincaré Conjecture, a famous problem in mathematics that had remained unsolved for over a century. His proof, published in 2003, was verified by the mathematical community and is considered a significant achievement in the field. Despite his accomplishments, Perelman is known for his reclusive nature and declined several prestigious awards, including the Fields Medal and a $1 million prize from the Clay Mathematics Institute. His decision to reject these honors has made him a unique figure in the world of mathematics.