Pooka

Phooka (Púca, Pooka):

If a human is enticed onto a phooka's back it has been known to give them a wild ride.  But unlike a kelpie, which will take its rider and dive into the nearest river or lake to drown and devour him, the phooka will do the unfortunate rider no real harm.  The Púca has the power of human speech, and has been known to give advice and lead people away from danger.  Though the phooka enjoys confusing and often terrifying humans, it is considered to be benevolent.

From Fantasy Creatures 

I first learned about Pooka’s from the movie “Harvey.”  Who says you can’t learn anything from T.V.