Donald Henry Gaskins (The Killer of Hitchhikers)
This man has killed 80 to 90 people. He did not just kill them right away, but also tortured them and mutilated them. He targeted hitchhikers. One day, a man saw him killing two young men and so he was reported to the police. After his trial, he was sentenced to death. It was changed to life without parole. The worst part is that he has continued to kill people while on jail. He has the record of being the only man to have killed a fellow inmate on death row.