Darkling

A Darkling is an omen of death which can be seen by those who wield The Power. The exact nature of Darklings was never elaborated upon in-universe; they could either be the actual soul of the dead person or they are merely illusions or manipulable dark spirits that can take the form of a dead person or any other person.

One such darkling was likely used by Chase Collins whenever he used his powers against the Sons of Ipswich, in the form of a boy he killed on his way to the Dells prior to the start of the film, as a way to either intimidate them, to frighten them, or to let them believe that it was one of their own behind it.

First, Caleb is visited by the darkling the day after feeling The Power being used by someone. It appears in his car and nearly causes him to have a car accident. The night after, he sees it a second time. Following him, Pogue sees it.

Trivia

 * It is unknown when darklings first arose.
 * It is unknown if darklings are actual dead souls or demonic specters.