(Post zombie apocalypse)-a tribe of humans
Culture: Drumming circles daily around an arena for their bravest brutes to slaughter their accepted foe, the zombie. Feasts of overcooked zombie flesh (to kill all of the zombie virus present). Wooden fortress that make this tribe in the far future look several millennium behind in technology. Instead of becoming a troublesome and unnatural foe that they seek to cure, this tribe has accepted that Zombies will continue to roam their land and, if the undead were to perish (be cured), this tribe would suffer as well.
Arkths or Ravagers: These are large landbound crablike creatures about the size of Grizzly Bears. They live partially in the astreal plane. Their food is magic. They can sense it at huge distances. Since spells and such are hard to eat (being in motion) and magical places are the equivalent of a sea of krill to them, they are looking for magic stashed in concrete places. Their primary food source is magic items, alchemical potions, and enchantments. They do a pretty good job of mangling/ eating the physical aspect of said items in the process of chowing down. These things will be the bane of dungeons everywhere, as they will slowly eat away much of the treasure (and the magical traps... so it can be advantagous to follow these things). Note: They will attack people with highly magical natures (i.e. high magic powers). They will probably kill the person in the process of sucking out the power.