Eidolon

The Shadowfell is a place with a long memory. Just as the Shadowfell town of Azartane remembers and incorporates elements of the ancient Material Plane town of the same name, so too do the deaths of a few powerful individuals leave imprints or echoes on the Shadowfell. Such echoes -- described by Aka as halfway between ghosts and archetypes -- are called eidolons, and are typically created when a very powerful person dies protecting something. The only eidolon thus far recorded is Oryx, the eidolon of King Clement I.