Walter Richard Sickert (31 May 1860 – 22 January 1942), born in Munich, Germany, was a painter who was a member of the Camden Town Group in London. He was an important influence on distinctively British styles of avant-garde art in the 20th century.

Sickert was a cosmopolitan and eccentric who often favoured ordinary people and urban scenes as his subjects. His oeuvre also included portraits of well-known personalities and images derived from press photographs. He is considered a prominent figure in the transition from Impressionism to Modernism.

Sickert's father, Oswald Sickert, was a Danish-German artist. His mother, Eleanor Louisa Henry, was an illegitimate daughter of the British astronomer Richard Sheepshanks.

The family had left Munich to settle in Britain at the time of the Great Exhibition, Oswald's work having been recommended by Freiherrin Rebecca von Kreusser to Ralph Nicholson Wornum, who was Keeper of the National Gallery at the time. The young Sickert was sent to University College School from 1870-1871, before transferring to King's College School, Wimbledon, where he studied until the age of 18. Though he was the son and grandson of painters, he first sought a career as an actor; he appeared in small parts in Sir Henry Irving's company, before taking up the study of art as assistant to James Abbott McNeill Whistler. He later went to Paris and met Edgar Degas, whose use of pictorial space and emphasis on drawing would have a powerful effect on Sickert's own work.

"Jack the Ripper" is the best-known name given to an unidentified serial killer who was active in the largely impoverished areas in and around the Whitechapel district of London in 1888. The name originated in a letter, written by someone 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 a journalist in a deliberate attempt to heighten interest in the story. Other nicknames used for the killer at the time were "The Whitechapel Murderer" and "Leather Apron".

Attacks ascribed to the Ripper typically involved female prostitutes from the slums whose 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 possessed anatomical or surgical knowledge. Rumours that the murders were connected intensified in September and October 1888, and letters from a writer or writers purporting to be the murderer were received by media outlets and Scotland Yard. The "From Hell" letter, received by George Lusk of the Whitechapel Vigilance Committee, included half of a preserved human kidney, supposedly from one of the victims. Mainly because of the extraordinarily brutal character of the murders, and because of media treatment of the events, the public came increasingly to believe in a single serial killer known as "Jack the Ripper".