Sir John Fielding (16 September 1721 – 4 September 1780) was a notable Englishmagistrate and social reformer of the 18th century. He was also the younger half-brother of novelist, playwright and chief magistrate Henry Fielding. Despite being blinded in a navy accident at the age of 19, John set up his own business and, in his spare time, studied law with Henry.
Appointed Henry's personal assistant in 1750, John helped him to root out corruption and improve the competence of those engaged in administering justice in London. They formed the first professional police force, the Bow Street Runners. Through the regular circulation of a 'police gazette' containing descriptions of known criminals, Fielding also established the basis for the first police criminal records department.
When Henry died in 1754, John was appointed magistrate at Bow Street in his place, becoming renowned as the "Blind Beak", and allegedly being able to recognize three thousand criminals by the sounds of their voices. He also continued to develop his ideas on crime prevention and youth employment, helping to found the Asylum for Orphan Girls in Lambeth in 1758. He was knighted in 1761.
A fictionalized Sir John Fielding is the protagonist of eleven historical detective novels (set in Britain's Georgian period), written by the American writer Bruce Cook, under the pseudonym Bruce Alexander.
John Fielding is an important character in the historical detective novel Death in the Dark Walk (1994), written by Deryn Lake.
John Fielding is a recurring supporting character in a series of Benjamin Franklin mysteries by Robert Lee Hall—set in London during the late 1750s. In many instances Fielding himself requests Franklin's help solving a murder.