Elizabeth "Long Liz" Stride (ne Gustafsdotter; 27 November 1843 30 September 1888) is believed to have been the third victim of the unidentified serial killer known as Jack the Ripper, who killed and mutilated at least five women in the Whitechapel and Spitalfields districts of London from late August to early November 1888.Unlike the other four canonical Ripper victims, Stride had not been mutilated following her murder, leading some historians to suspect Stride had not actually been murdered by Jack the Ripper. However, Stride's murder occurred less than one hour before the murder of the Ripper's fourth canonical victim, Catherine Eddowes, within walking distance, and her act of murder is suspected to have been disturbed by an individual entering the crime scene upon a two-wheeled cart. In addition, both women had been murdered by slash wounds to the throat, leading most authors and researchers to consider Stride to be the third of the Ripper's canonical five victims.Stride was nicknamed "Long Liz". Several explanations have been given for this pseudonym; some believe it sources from her married surname (a stride being a reference to a long step), while others believe this is a reference to either her height, or her general facial structure.

Jack the Ripper was an unidentified serial killer active in the impoverished districts in and around Whitechapel in the East End of London in 1888. In both criminal case files and the contemporary journalistic accounts, the killer was called the Whitechapel Murderer and Leather Apron.

Attacks ascribed to Jack the Ripper typically involved female prostitutes who lived and worked in the slums of the East End of London. Their throats were cut prior to abdominal mutilations. The removal of internal organs from at least three of the victims led to proposals that their killer had some anatomical or surgical knowledge. Rumours that the murders were connected intensified in September and October 1888, and numerous letters were received by media outlets and Scotland Yard from individuals purporting to be the murderer. The name "Jack the Ripper" originated in a letter written by an individual claiming to be the murderer that was disseminated in the media. The letter is widely believed to have been a hoax and may have been written by journalists in an attempt to heighten interest in the story and increase their newspapers' circulation. The "From Hell" letter received by George Lusk of the Whitechapel Vigilance Committee came with half of a preserved human kidney, purportedly taken from one of the victims. The public came increasingly to believe in a single serial killer known as "Jack the Ripper", mainly because of both the extraordinarily brutal nature of the murders and media coverage of the crimes.

Extensive newspaper coverage bestowed widespread and enduring international notoriety on the Ripper, and the legend solidified. A police investigation into a series of eleven brutal murders committed in Whitechapel and Spitalfields between 1888 and 1891 was unable to connect all the killings conclusively to the murders of 1888. Five victims—Mary Ann Nichols, Annie Chapman, Elizabeth Stride, Catherine Eddowes, and Mary Jane Kelly—are known as the "canonical five" and their murders between 31 August and 9 November 1888 are often considered the most likely to be linked. The murders were never solved, and the legends surrounding these crimes became a combination of historical research, folklore, and pseudohistory, capturing public imagination to the present day.