Marie Curie was a Polish-born physicist and chemist who is best known for her pioneering work on radioactivity. She was the first woman to be awarded a Nobel Prize, and the first person to receive two Nobel Prizes in different fields: physics in 1903 and chemistry in 1911. Curie's discoveries and contributions to the understanding of radioactivity were groundbreaking, and she is considered one of the most important scientists of the 20th century. Her work led to the development of new medical treatments, and her legacy continues to inspire scientists around the world.