Marie Curie was a physicist and chemist whose genius fundamentally changed our understanding of the atom. She coined the term 'radioactivity' and discovered two new elements: polonium and radium. Her genius for experimental science led her to develop mobile X-ray units (Little Curies) to treat soldiers during World War I. Curie is the only person to win two Nobel Prizes in different scientific fields (Physics and Chemistry). Despite the severe health risks posed by radiation exposure—which were unknown at the time—she continued her research until her death. Her notebooks are still so radioactive today that they must be stored in lead-lined boxes.