The idea of a creature which gets back up after it appears to be dead is quite popular in fiction (cases in point; Not Quite Dead monsters and protagonists). It makes them seem more intimidating, ensures that the hero is challenged, and in some cases keeps things more family friendly by making sure that no one actually dies. Note that these shouldn't be confused with Respawning Enemies, which can be defeated normally but are constantly being replaced by their fellows. Examples of Reviving Enemy include: