Between August and November of 1888, at least five women were murdered under the alias Jack the Ripper in the Whitechapel neighborhood of London's East End. One of the most well-known unresolved riddles in English criminal justice is this case.

A few dozen killings that occurred between 1888 and 1892 have been speculatively linked to Jack the Ripper; however, police have only connected five of the killings, all of which occurred in 1888. Mary Ann Nichols (whose body was discovered on August 31), Annie Chapman (found September 8), Elizabeth Stride (found September 30), Catherine (Kate) Eddowes (found September 30), and Mary Jane Kelly (found November 9) were the victims known as the "canonical five." At the time, it was widely believed that all of the victims were prostitutes, with the exception of Kelly, who was killed while begging on the street.

Subsequently, this assumption was taken for granted in books about the killings, many of which were based on fake claims and documents and presented speculations as to the true identity of Jack the Ripper in addition to gruesome details of the murders he perpetrated. In a novel twist on the genre, Hallie Rubenhold, a British social historian, argued in The Five: The Untold Lives of the Women Killed by Jack the Ripper (2019) that Nichols, Chapman, and Eddowes were not prostitutes; Stride had only infrequently turned to prostitution during times of extreme poverty and mental anguish (though there's no proof she was soliciting at the time of her murder); and Kelly was the only one of the five who could be proven to be a verified prostitute.

According to Rubenhold, the idea that Jack the Ripper killed prostitutes arose from the misogynistic and class-based stereotypes prevalent in the Victorian era.

The victim's throat was severed in each case, and the body was typically disfigured in a way that suggested the murderer knew something about the anatomy of humans. A human kidney half that might have been taken from a murder victim was once mailed to the police. A person posing as the murderer and going by the name Jack the Ripper also sent a string of obscene notes to the authorities.

To no effect, arduous and occasionally odd attempts were made to locate and apprehend the murderer. The London police commissioner and the home secretary faced intense public criticism for their inability to apprehend the murderer, leading to their resignation shortly after.
Since known cases of serial killing were far less common at the time than they are now, the case has continued to captivate the public's attention. 

Jack the Ripper has served as a theme for many plays and books. The most well-known was perhaps Marie Adelaide Lowndes' horror novel The Lodger (1913), which served as the basis for many movies, including Alfred Hitchcock's The Lodger: A Story of the London Fog (1927).
The most frequently mentioned suspects are: Michael Ostrog, a Russian criminal and physician who was committed to an asylum due to his homicidal tendencies; Aaron Kosminski, a Polish Jew who lived in Whitechapel and was known to have strong animosity toward women; and Montague Druitt, a teacher and barrister with a fascination for surgery who was allegedly insane, vanished after the last murders and was subsequently discovered dead.