These creatures can be found throughout the mythology of many different regions. Then tend to be poor looking animals; the ones that appear to be old and decrepit or underfed. The hero taking a chance on them learns that they can travel faster than the wind and their advice which is seldom followed is always sage. Generally at the end of the story once the hero has learned their lesson the animal will shift into a beautiful man or woman as appropriate for the hero in question, or else offer their sister as a reward.
It's not unknown for the animal person in question to have been transformed by an evil magician - either to hide them from rescuers, to punish them for their opposition or possibly to force some service from them (maybe in repayment for a witch boon). Some versions of the hag-riding myth involve the victim actually being transformed into a horse.
Theoretically, the transformation could be the work of a good or morally ambiguous magician as well - inflicting a punitive or educational transformation on the subject (in some versions of Beauty and the Beast the Beast was transformed as a punishment for using his own beauty to toy with the affections of a wizard's daughter) - or to hide them from enemies.
Examples of shape-shifting animals include:
Various Fairy tales including:
Game and Story Use
- Perhaps the PCs have been gifted with an old broken down mare as their reward for a particularly hard quest.
- Here they could have to learn that not everything is what it appears to be.
- Perhaps they've been hired to retrieve the beloved animal of some sultan- only to discover that the animal has a mind of its own about where it will be going.
- In a more modern game they could be taking the shape of battered old cars or old out of date laptops.