Sir Hugh William Bell Cairns KBE FRCS (26 June 1896 – 18 July 1952) was an Australian neurosurgeon.

His concern about despatch rider injuries sparked research which led to increased use of motorcycle helmets.

He was a key figure in the development of neurosurgery as a speciality, the formation of the Oxford University Medical School, and the treatment of head injuries during the Second World War.

[3] While at the London Hospital and in Oxford, Cairns trained US-born surgeon Joseph Buford Pennybacker, who in 1952 took over as director of the Radcliffe's neurosurgery department, a job he held until he retired in 1971.

There is a road named after him at Bedford Park, South Australia, adjacent to Flinders Medical Centre.