Sir William Arbuthnot Lane, 1st Baronet, CB, FRCS (4 July 1856 – 16 January 1943) was a British surgeon and physician. He mastered orthopaedic, abdominal, and ear, nose and throat surgery, while designing new surgical instruments toward maximal asepsis. He thus introduced the "no-touch technique", and some of his designed instruments remain in use.

Lane pioneered internal fixation of displaced fractures, procedures on cleft palate, and colon resection and colectomy to treat "Lane's disease"—now otherwise termed colonic inertia, which he identified in 1908—which surgeries were controversial but advanced abdominal surgery. During World War I, as an officer with the Royal Army Medical Corps, he organised and opened Queen Mary's Hospital in Sidcup, which pioneered reconstructive surgery. The late-Victorian and Edwardian periods' preeminent surgeon, Lane operated on socialites, politicians, and royalty. Lane thus attained baronetcy in 1913.

In the early 1920s, as an early advocate of dietary prevention of cancer, Lane met medical opposition, resigned from British Medical Association, and founded the New Health Society, the first organisation practising social medicine. Through newspapers and lectures, sometimes drawing large crowds, Lane promoted whole foods, fruits and vegetables, sunshine and exercise: his plan to foster health and longevity via three bowel movements daily. Tracing diverse diseases to modern civilization, he urged the people to return to farmland.

For his New Health, Lane eventually became viewed as a crank. Lane's explanation of the association between constipation and illness as due to autointoxication is generally regarded by gastroenterologists as wholly fictitious, and Lane's earlier surgeries for chronic constipation have been depicted as baseless. Yet constipation remains a major health problem associating with diverse signs and symptoms, including psychological—sometimes still explained as Lane's disease—and total colectomy has been revived since the 1980s as a mainstream treatment, although dietary intervention is now the first line of action.

William Arbuthnot Lane was born in 1856 in Fort George near Inverness, Scotland, as the eldest of the eight children of Benjamin Lane, a military surgeon enlisted to the British Empire. William attended schools in eight countries on four continents—Ireland, India, Corfu, Malta, Canada, South Africa, and others—while his family followed the army regiment. Amid his mother's bearing seven children in rapid succession after him, William was often left in the care of military personnel. At age 12, he was sent to boarding school at Stanley House School, Bridge of Allan in Scotland.

In 1872, his father arranged for him, age 16, to study medicine at Guy's Hospital. Apparently shy and appearing young even for his age, William initially had some troubles with fellow students, but they rapidly recognized his exceptional abilities. Soon, he was persuaded to switch to surgery, however, a surer career than medicine. Later, he received the degrees bachelor of medicine and master of surgery from the University of London.

In 1877, at age 21, he qualified as a member of the Royal College of Surgeons, and began to practise in Chelsea, London, at the Victoria Hospital for Children. In 1883, Lane became a Fellow of Royal College of Surgeons and joined Great Ormond Street Hospital, where he was consultant until 1916. In 1888, at age 32, Lane returned to Guy's Hospital as anatomy demonstrator and assistant surgeon, and remained with Guy's for most of his career.

Lane became especially known for internal fixation of displaced fractures, neonatal repair of cleft palate, and developing colectomy, which, although highly controversial and opposed by most surgical peers, notably advanced abdominal surgery. Lane collaborated with Down Brothers to design a number of surgical instruments, including screw driver, periosteal elevator, tissue forceps, intestinal anastomosis clamp, bone-holding forceps, and osteotome. For his surgery on British royalty, he was awarded baronetcy in 1913.