Satan, the ultimate scapegoat and boogeyman. Centuries ago, the Catholic Church used the Prince of Darkness to scare western Europe into submission, and as a convenient excuse to torture and execute those who spoke out against the organization's hegemony. In the 1980s, a rash of news stories and urban legends about occult rituals, dark magic, and brutal murders shook America. Little of it was true, and the hysteria is now know as the Satanic Panic. From metal bands that use Satanic imagery and lyrics to the criminals on this list who invoke the devil as their guiding hand, Lucifer has become something of a catchall of evil in the Western world.
When it comes to devil worship and possession, things get very messy, very fast; it's hard to tell someone they weren't possessed if they totally believe they were. Each possessed killer on this list blamed their crimes on the devil. Whether or not the people on these people were telling the truth about whatever caused them to commit their crimes doesn't matter. What does matter is they all committed truly heinous crimes, supposedly because the devil told them to.