The Ancient race, now extinct. This race appears to have created much of the near-forgotten technology of the world. Or if not its creator, they at least knew its purpose and how to use it. The gate to the Spirit World, the drainstones, and the metal ship in the haunted forest around Shadetale are examples of such technology.
These ancient peoples were capable of traveling between reality and Gorsus, the Spirit World. Did they only accomplish this with use of the gates and drainstones, or did they have another way? Were those gates always open in their time, as the Runeseeker trapped in Gorsus in Hood Episode Four tells the Hunter he became trapped after entering the gate that was open.
The Dead Race once received 'rites' which apparently allowed them to go elsewhere than the Spirit World, or at least have peace after death; however, in Hood Episode Four the Ancient spirit tells the Hunter they are trapped in the Spirit World because they did not receive those rites and now never will as their kind is all extinct.