The famous physicist renowned for his discovery of radioactivity is Marie Curie. Curie was the first individual to win Nobel Prizes in two different scientific fields: Physics (1903) and Chemistry (1911). Her groundbreaking research on elements like polonium and radium laid the groundwork for advances in both nuclear physics and medical treatments such as cancer therapies. Curie's work significantly changed the understanding of atomic science and opened up new realms of research, although it also posed health risks that ultimately impacted her own life.