The pooka is a shapeshifting Celtic fairy known for its mercurial nature and ability to bring both weal and woe.  Pookas can take a number of different forms, but the most popular are that of a horse, cat, rabbit, raven, fox, wolf, goat, goblin, or dog; however, even in human form they are said to display animalistic features.  These capricious fairies are known to be very dangerous, but a particularly clever person is said to be able to occasionally trick them into service.  In this endeavor it is best to be ready to flee after gaining whatever favor one is after from the pooka.