The well-known scientist credited with advancing the field of immunology is Louis Pasteur. He is famous for developing the germ theory of disease, which paved the way for understanding how pathogens cause illness. Pasteur's work on vaccinations, particularly for rabies and anthrax, significantly contributed to the development of immunization techniques. His methodologies laid the groundwork for modern vaccinology and influenced countless scientific advancements in the prevention and treatment of infectious diseases, marking him as a pioneer in the field of medical science and public health.