Ghost

A ghost is the spirit of a deceased humanoid. This type of undead is incorporeal in nature and only vulnerable to conventional weapons on the Ethereal Plane. a Ghost Brute is a ghost of an animal, plant, or Magical beast that is stuck to the material plane.

A ghost is a creature on two planes, the material and the Astral Plane. A ghost's connection to the material plane is severed when you destroy it, but in a few days the ghost will usually come back. Ghosts are a repetitive nusance for those who live in one's particular haunt.