The Púca or Pooka / Puka / Phouka

The Púca are one of the most feared and mischievous of all the faeries in Ireland. It is a changeling who appears in many guises, the most comman a sleek black horse with amber eyes. With this form it can cover huge areas of land as it charges through the countryside in the dark of night breaking fences scattering and scaring farm animals and trampling crops. It can also take the form of a huge Eagle, a giant hairy Bogeyman or a large hairy goat. Sometimes it takes the form of like that of some of the smaller faeries, from all accounts similar to a deformed hobbit like creature. In any of these forms the Púca can speak with humans, think Mr Ed the talking horse...but evil.
If there are any late night travelers on the road the Púca picks them up as it thunders down the road and and throws them into drains and into bogs. Just by looking at Chickens he can stop them laying eggs and stop cows from giving milk. It has the power of speech and will often call to peoples houses before it starts its nightly runs to demand company, if denied he will destroy all your property. Sometimes they are not evil a Púca will sometimes come to the aid of people and other times have come to their aid to warn them of something that might befall them.
The only time that a mortal has been able to ride one of them and tame it was the the High King of Ireland Brian Boru. He got the Púca to agree never to attack a mortal, unless they were drunk and on evil business. This did not last for many years and they still roam the land.