Aileen Carol Wuornos was an American serial killer. In 1989–1990, while engaging in street prostitution along highways in Florida, she shot dead and robbed seven of her male clients. Wuornos claimed that her clients had either raped or attempted to rape her, and that the homicides of the men were committed in self-defense. Wuornos was sentenced to death for six of the murders. She was executed on October 9, 2002, by lethal injection after spending more than 10 years on Florida's death row.

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.