The phooka is a tricksy shape-shifting goblin of Irish lore. He can take on various forms such as a dog, bull, or even an eagle. Most frequently, however, he appears as a black horse or pony with glowing eyes. He approaches unwary travelers and offers them a ride on his back. Once he has them, the phooka then takes them on a harrowing gallop across the countryside before unceremoniously dumping them into a ditch or mire. Then he laughs at them. If he had fingers, I imagine he’d point, too.
The phooka seems to be a benign cousin to the kelpie, who also appears as a horse to carry unwary travelers upon his back. However, unlike the phooka who seems to be just having a bit of fun, the kelpie will take his passengers to a lake or river and drown them.
Source: Froud, Brian; Lee, Alan, Faeries, Harry N. Abrams, Inc., 1978.