Sir Harold Jalland Stiles KBE FRCS FRCSE FRSE (21 March 1863 – 19 April 1946) was an English surgeon who was known for his research into cancer and tuberculosis and for treatment of nerve injuries.

[5] He trained for six months under Professor Theodore Kocher in Bern, where he learned to follow the aseptic system of surgery rather than Listerian antisepsis.

[2] He taught at the Children's Hospital for many years, and during this period he or his assistants published important papers on surgical tuberculosis, earning him recognition throughout the medical world.

[11] During World War I (1914–1918) Stiles was a Colonel in the Royal Army Medical Corps in France, and then Director of Military Orthopaedics for Scotland.

[2] He was responsible for treating wounded soldiers in the Military Surgical Division at the Bangour hospital, and for his achievements was awarded a knighthood in the 1918 New Year Honours and made a Knight Commander of the Order of the British Empire in 1919.

[1][4] In 1919 he succeeded Prof Francis Mitchell Caird as Regius Professor of Clinic Surgery at Edinburgh University,[12] holding this position for six years before retiring.

[2] He was also appointed to the Edinburgh Royal Infirmary, where he organized a surgical unit and pathological laboratory and provided practical courses in surgery.

Stiles showed that tuberculosis of bones, joints and cervical lymph nodes was often caused by the bovine form of the tubercle bacillus.

[2] Distinguished American orthopedic surgeon Paul B. Steele served under Harold Stiles from 1917 to 1918, where he was taught the techniques of war surgery before joining the army in France.