Sir William Macewen, CB, FRS, was a Scottish surgeon. He was a pioneer in modern brain surgery and contributed to the development of bone graft surgery, the surgical treatment of hernia and of pneumonectomy (removal of the lungs).
He was born near Port Bannatyne, Isle of Bute, on 22 June 1848 and studied at the University of Glasgow, receiving a medical degree in 1872. He was greatly influenced by Joseph, Lord Lister (1827–1912), who revolutionised surgery by developing antisepsis, by the use of phenol, thus decreasing drastically the enormous mortality of surgical patients due to infections. By following Lister and adopting systematically the use of scrubbing (deep cleansing and disinfection of hands and arms), sterilisation of surgical tools, use of surgical gowns, and (recently discovered) anaesthesia, Macewen became one of the most innovative surgeons of his time and was able to greatly advance modern surgical technique and improve the recovery of patients.
In 1875, he became an assistant surgeon at the Glasgow Royal Infirmary, being promoted to full surgeon in 1877. In 1881 he was appointed lecturer on Systematic Surgery at the Royal Infirmary School of Medicine. In 1883 he was appointed as Surgeon to the Royal Hospital for Sick Children in Glasgow. In 1892 Macewen became Regius Professor of Surgery at the University of Glasgow (the post which Lister had held when Macewen was a student) and transferred his surgical activities to the Western Infirmary.
In 1916 Macewen helped to found the Princess Louise Scottish Hospital for Limbless Sailors and Soldiers in Erskine (now the Erskine Hospital), near Glasgow, which was urgently needed to treat the thousands of military that lost their limbs in the First World War. Macewen was its first chief surgeon and with the help of engineers and workers of the nearby Yarrow Shipbuilders, he designed the Erskine artificial limb. He trained a team of pattern-makers to manufacture them for the hospital.
He died in Glasgow on 22 March 1924. He lived at Garrochty on the Isle of Bute until his death, and was buried nearby in the churchyard of St Blane's Chapel.