Peter Kürten was a German serial killer, known as "The Vampire of Düsseldorf" and the "Düsseldorf Monster", who committed a series of murders and sexual assaults between February and November 1929 in the city of Düsseldorf. In the years before these assaults and murders, Kürten had amassed a lengthy criminal record for offences including arson and attempted murder. He also confessed to the 1913 murder of a nine-year-old girl in Mülheim am Rhein and the attempted murder of a 17-year-old girl in Düsseldorf.

A serial killer is a person who murders three or more people, with the killings taking place over a significant period of time between them. The serial killers' psychological gratification is the motivation for the killings, and many serial murders involve sexual contact with the victims at different points during the murder process. The Federal Bureau of Investigation (FBI) states that the motives of serial killers can include anger, thrill-seeking, financial gain, and attention seeking, and killings may be executed as such. The victims tend to have things in common such as, demographic profile, appearance, gender or race. The FBI will focus on particular patterns that the serial killers follow throughout their murders. They will then use on the patterns they find for key clues into finding the killer along with their motives. Although a serial killer is a distinct classification that differs from that of a mass murderer, spree killer, or contract killer, there are overlaps between them.