It’s scary to think there are active serial killers out there right now. In history, there are unidentified serial killers everyone knows about, the Jack the Ripper and the Zodiac Killer. But there are also less famous serial killers that haven’t been caught, like Charlie Chop-Off, the West Mesa Bone Collector and the Servant Girl Annihilator. WatchMojo counts down ten of the most dangerous serial killers that were never identified.