Gladys Maude Winifred Mitchell (21 April 1901 – 27 July 1983) was an English writer best known for her creation of Mrs Bradley, the heroine of 66 detective novels.

Fêted during her life (called "the Great Gladys" by Philip Larkin), her work has been largely neglected in the decades since her death.

Gladys Maude Winifred Mitchell was born in Cowley, Oxford on 19 April 1901 to James, a market gardener of Scottish parentage, and Annie.

Mitchell was an early member of the Detection Club along with G. K. Chesterton, Agatha Christie and Dorothy L. Sayers and throughout the 1930s was considered to be one of the "Big Three women detective writers", but she often challenged and mocked the conventions of the genre – notably in her earliest books, such as the first novel Speedy Death, where there is a particularly surprising twist to the plot, or her parodies of Christie in The Mystery of a Butcher's Shop (1929) and The Saltmarsh Murders (1932).

Her plots and settings were unconventional with Freudian psychology, witchcraft (notably in The Devil at Saxon Wall [1935] and The Worsted Viper [1943]) and the supernatural (naiads and Nessie, ghosts and Greek gods) as recurrent themes.

A BBC television series, The Mrs Bradley Mysteries (starring Diana Rigg) was produced in 1999; however, the characteristic cackle and crocodilian looks were absent, and the plots and characters were changed.

Minnow Press continued their Mrs Bradley Collectors' Series with the reissue of the scarce 1939 title Printer's Error in 2007, The Worsted Viper in 2009, and Hangman's Curfew in 2010.