[custom_adv] The stories of history's worst serial killers are more terrifying than any horror story could ever be. No make-believe monster will ever match that soul-chilling feeling that seeps in when we read a headline that says "Serial Killer on the Loose." [custom_adv] It's not just that serial killers are real and not at all make-believe. It's something else that truly drives the terror into our souls. It's the thought that they actually enjoy it. [custom_adv] Perhaps that's why they fascinate us so much. We can understand a crime of passion. The idea of bursting into a rage and losing control is only too familiar – but a serial killer is different. [custom_adv] A serial killer doesn't kill out of hate or anger. A serial killer moves from victim to victim, purely out of a desire to kill. For them, it's a joy, or at least a compulsion. That's where the terror of serial killer stories truly lies. It's not just the gore and the violence of the act – it's the joy. It's the disturbing glee that a man like Edmund Kemper gets when he drives a blade through another person's neck. [custom_adv] For many of history's scariest serial killers, it's not just that they want to kill, it's also that they have to. It's a pulsing urge that beats inside of them. It's a demon torturing them from the inside, one that won't stop until they kill. [custom_adv] And then they do – and there's release. For the worst serial killers, there's no horror or fear in the act of killing. When the Son of Sam, David Berkowitz, killed his first victim, he was so filled with euphoria that he sang on his way home. He felt nothing but release. [custom_adv] Strictly speaking, a serial killer is someone who murders at least two people in separate events that occur at different times. While “serial murder” is not formalized by any legal code, the crimes of serial killers have often been seized on by the media and the public consciousness—especially in cases where there are many victims or the murders are carried out in gruesome fashion. [custom_adv] If cop shows and forensic dramas have taught us one thing, it's that serial killers are a breed apart from other human beings. They're the monsters that hide in the shadows, the diabolical predators of otherwise peaceful times.