Greek mythology is peopled with fantastic creatures—from the Cyclops and the Lotus Eaters that Odysseus encountered on his voyage home after the Trojan Wars, the Sirens he avoided, and the six-headed monster Scylla, to satyrs, centaurs, and dragons.

Celtic, Norse, and Germanic myths aren’t short on such creatures either. Elves—both light and dark—giants, trolls, mermaids, dwarfs, faeries, and individual monsters such as Grendel and his mother in Beowulf, all have found places in fantasy from time to time.

Of course the current trend is toward the inclusion of vampires, werewolves, and zombies—the latter apparently having their origins in Africa while the first two stem from Europe.

Writers take varying liberties with these creatures, sometimes using the old as the basis of something new. George Bryan Polivka invented firefish in his Trophy Chase Trilogy—creatures that seems to be some mix of the Loch Ness Monster (or perhaps the Sea Monster in C. S. Lewis’s Voyage of the Dawn Treader) and dragons. In the DragonKeeper Chronicles Donita Paul created “minor dragons” which are dragons the size of large birds with individual talents that benefit others such as their keeper.

Ms. Paul also received considerable notoriety for creating an array of new races, from Emerlindians who are born pale and darken with age to the tiny Kimens, no more than two feet tall. Spec Faith’s recent guest blogger, Jonathan Rogers, concocted his own race of Feechie to inhabit his world of Corenwald.

Other writers, such as Mary Shelley with her Dr. Frankenstein’s monster, have invented individual creatures that have become legendary.

The question is, do readers prefer the old? Or are they just as engaged by the new?

What qualities would make new creatures as captivating as the ones from ancient legends?

First, they must be believable. If they exist as fantasy creatures in this world, they require some sort of explanation (Spiderman acquired his powers because of the bite of a radioactive spider, Superman came from another planet). If they exist in a fantasy world, they must have their own culture and history.

Second, their “special” qualities—their magic or power—must be integral to the story. They cannot be present as window dressing.

Third, those which are evil must be significantly frightful. In other words, they must be formidable opponents, not token obstacles. Those which are good must be powerful but not in such a way as to render unnecessary any involvement by the protagonist.

Fourth, they must have unique properties that keep them from being ancient creatures disguised by a different name.

Fifth, an invented fantasy creature must have a unique voice, not a reworking of a more famous being such as Golum or Aslan.

So which do you prefer in your reading, ancient creatures reinvented or new creatures freshly fashioned? Who are some of your favorites?

For writers, do you rely on creatures of old? Do you give them your own twist? If so, how are yours different? Or do you create your own creatures, and if so, what made you decide to do so?