English police magistrate and the younger half brother of novelist Henry Fielding, noted for his efforts toward the suppression of professional crime and the establishment of reforms in London's administration of criminal justice.

John Fielding was blinded in an accident at the age of 19. Despite this handicap he was appointed a magistrate in London, at first as his brother's assistant, about 1750, and soon became locally famous as the “Blind Beak,” who was reputedly able to recognize some 3,000 thieves by their voices. With his brother he was a founder of the Bow Street Runners, and he persuaded the government to contribute to the expenses of his small force of professional detectives. He also provided for the circulation among the police and the public of descriptions of offenders.

A pioneer in the treatment of juvenile offenders, Fielding sought to analyze and remove the causes of crime and advocated a system of stipendiary magistrates that was adopted in 1792. His only authentic writings published are A Plan for Preventing Robberies Within 20 Miles of London (1775); An Account of the Origins and Effects of a Police . . . (1758); and Extracts From Such of the Penal Laws as Relate to the Peace and Good Order of This Metropolis (1768). He was knighted in 1761.