Some years ago a dark cult was founded in the Forecastle area of Hahvrensburg. The cultists were defeated by a band of heroes. A month after the heroes left the city and went on about their business, something massive came out of the earth.
Undead are, simply put, among the most horrific things one can think of. Can you imagine anything more frightening than a being which is dead and yet still walks? Can you imagine the horror of being faced by the hollow shell of being, a hollow shell which must feed?
Unseen and striking from suprise, this creature is on its way to becoming a legend.
Awakened by a Curse, fed by the cries and anger of children, this creature now roams the world.
Think of any bizzare life-form, WHATEVER life-form that lives a not-so-standard way. Not the way common sense would expect it. Make it in some way logical or not, just forget the boring everyday logic.
The Eternals are one of the few races who survived the awakening of the Gods and the fall of Prime Creation. They were solitary, but powerful, weavers of essence and were locked in a bloody war with the Other Ones, another race which survived the Gods.
A slow, stupid creature that crawls onto people and latches onto them, often on feet, hands, and other extremities, numbing down the area and slowly feeding on it. It's easy to avoid while awake, but nearly impossible to remove once attached. Many an adventurer has been forced to hack off an arm or leg after waking with a Stoneleech wrapped around it. Sleep with one eye open! (This idea came from "Wizard's Rule")