William Stewart Halsted (1852–1922) was an American surgeon, born in New York City, and one of the “Big Four” founding professors of Johns Hopkins Hospital. He studied medicine at Columbia University (graduating in 1877) and refined his skills in Europe (1878-1880). He pioneered aseptic surgical techniques, adopted German surgeons' training system and introduced the first American surgical residency program at Johns Hopkins in 1889. He established the Halstedian principles: gentle tissue handling, meticulous hemostasis, and layered wound closure. In 1889, he also became the first Chief of Surgery at Johns Hopkins. He introduced rubber surgical gloves (1890), initially to protect his nurse and future wife from skin irritation. Halsted also made major contributions to breast cancer surgery (Halstedian radical mastectomy) and the use of local anesthesia, though his experiments led to lifelong cocaine and morphine addiction. He died in 1922 in Baltimore, leaving a legacy as the architect of American modern surgical training and technique.