William Stewart Halsted was an influential American surgeon born in 1852. He is best known for his pioneering work in the field of surgery, particularly in the development of the Halsted mastectomy, a radical procedure for breast cancer treatment. Halsted also contributed to the advancement of surgical techniques and anesthesia, emphasizing the importance of aseptic practices in the operating room. Halsted was a key figure in the establishment of the Johns Hopkins Hospital and its medical school, where he served as the first chief of surgery. His innovative approaches laid the groundwork for modern surgical practices, and he is often regarded as one of the founding figures of contemporary surgery.