Lich

These are people who some way or another were possessed with Celestial energy. Some can survive this celestial energy, others can't. Their body's response to this energy is to decompose but the energy keeps them alive. This energy can be harnessed to wield magic. They further their own power at any cost, having no interest in the affairs of the living except where those affairs interfere with their own. They hunger for long-forgotten knowledge and the most terrible secrets. Because the shadow of Death doesn’t hang over them, they can conceive plans that take years, decades, or centuries to come to fruition.
  A lich is a gaunt and skeletal humanoid with withered flesh stretched tight across its bones. Its eyes succumbed to decay long ago, but points of light burn in its empty sockets. It is often garbed in the moldering remains of fine clothing and jewelry worn and dulled by the passage of time.