When we are forced to think about the most evil people who have ever lived, our brains usually turn to the serial killer. Modern horror movies often focus on these very worst of people, those who calculatedly seek out innocent victims to slaughter.
Still, "serial killer" has a very specific definition, as outlined by the FBI:
• one or more offenders
• two or more murdered victims
• incidents should be occurring in separate events, at different times
• the time period between murders separates serial murder from mass murder
That means that these famously awful people cannot be considered serial killers:
Actual Crimes: Necrophilia, Desecration of Human Remains, Grave Robbery
Number of Deaths Caused: 2
Gein confessed to killing two women, but the grisly, unnatural details of his crimes were enough to confer upon him the same disgust reserved for serial killers and mass murders. His notorious relics, including furniture made from human skin and bones, have influenced many movies from Psycho to The Texas Chainsaw Massacre.
See the Terrible Story on Screen: Deranged (1974), Ed Gein: The Butcher of Plainfield (2007), Ed Gein (2001)
Actual Crimes: Grievous Bodily Harm, Incitement to Violence
Number of Deaths Caused: 10
Despite never having delivered any killing blows himself, Charles Manson was - quite rightly - charged with 7 counts of first degree murder for his role in the killings of pregnant actress Sharon Tate, Leno & Rosemary LaBianca and others.
See the Terrible Story on Screen: Manson (1973), Charles Manson Superstar (1989), Helter Skelter (1976)
Actual Crimes: Cult Leader, Negligent Homocide
Number of Deaths Caused: 900+
Jones created his own cult and moved them from California to his own compound in Jonestown, Guyana. Fearing his power was declining, Jones ordered his followers to commit 'revolutionary suicide,' persuading them to drink cyanide-laced Kool-Aid. Those who refused were shot or given lethal injections by Jones' inner circle.
See the Terrible Story on Screen: Guyana Tragedy: The Story of Jim Jones (1980), Guyana: Cult of the Damned (1979), The Sacrament (2013)