Marie Curie was a physicist and chemist, who helped pioneer the field of radioactivity and was the first person honored with two Nobel Prizes - in physics and chemistry. She was also the first female professor at the University of Paris. Her achievements include the creation of a theory of radioactivity (a term she coined), techniques for isolating radioactive isotopes, and the co-discovery of two new chemical elements; polonium, and radium. 
"Unusually at such an early age, she became what T.H. Huxley had just invented a word for: agnostic." - From Marie Curie (pp. 19, 1974) by Robert William Reid Reid, Robert William.
NOTE: There are many articles on the Internet, which identify Curie as an "anticlerical atheist." It's unclear where this label came from, but none of the articles cite supporting evidence and should be considered baseless until additional evidence is brought forth.