From the movie the Exorcist, the ekimmu spirit is often the source of possessed victims.

The ekimmu shows up in Babylonian and Assyrian demonology. The name means “that which is snatched away.” This invisible spirit is not allowed into the underworld, so it wanders around on earth. Usually people that are buried improperly, or not buried at all, or dying a violent death can become ekimmu. This includes people that died in battle, murder victims, drowning, etc. They will go to their family’s house at night and cause major damage and destruction. They sometimes cause death to everyone in the house. They can also take possession on a person, which is difficult to exorcise it out. They can be destroyed with wooden swords, or any other wooden weapons.