A serial killer is someone that has killed more than three people in a repeated fashion and their characteristics are typically anti-social behaviour, psychopathic, narcissistic, paranoid and often very good at hiding these qualities from others. Most famous UK killer, Jack the Ripper, 1880s, real name unknown. Most famous USA Killer, Ted Bundy, 1970s. Most prolific UK Killer, Harold Shipman, estimated 250 deaths. Most prolific USA Killer, Charles Cullen, estimated 400 deaths. It is believed that there may be 50 serial killers at large at any one time. Rhona Smith wanted to set a record and not be caught. Her goal was 500 victims.