We now return to two of our more cinematic undead creatures: ghosts and mummies. Aside from being horror-film staples, they don’t have a lot in common with each other, except for one thing: each is bound to a specific location. A ghost has “unfinished business” and haunts an area closely related to whatever trauma it needs to resolve; it’s compelled by the urge to resolve this trauma. A mummy is the guardian of a tomb or other burial place, compelled to punish transgressors against either the tomb itself or, sometimes, the person buried there. (In the latter case, the mummy may leave the tomb to hunt down the transgressor. In the former, it always stays put.)
Ghosts may be malicious, but they don’t have to be. (A malicious ghost that for some reason is permanently prevented from resolving the trauma connected with its death may end up as a poltergeist instead.) They may want to punish people who wronged them in their previous lives, but they may also be sorrowful, lonely, lost or even deceiving themselves that they’re still alive. Revenge against those who wronged them might satisfy them, but so might making amends to those whom they wronged. You really can’t have a decent ghost without a backstory.