Ruth the Betrayer
Ruth the Betrayer; or, The Female Spy, by Edward Ellis was the first fictional female detective story. It was published as a penny dreadful in 52 parts in 1862-63 by John Dicks, and the British Library's single-volume compilation copy was acquired on 28 February 1863. It therefore predates Andrew Forrester's The Female Detective and W.S. Hayward's The Revelations of a Lady Detective, both of 1863/4. Ruth Trail, the protagonist, is "a female detective – a sort of spy we use in the hanky-panky way when a man would be too clumsy". See also
Barry Ono
List of female detective characters

Footnotes

Fictional British police detectives
Fictional English people
Literary characters introduced in 1862
Female characters in literature