A Phooka is a very dangerous and often violent shapeshifting trickster from Celtic myth, known for their ability to change into great fearsome black animals so that they can scare humans. Some Phookas take a liking to humans and just play harmless pranks (like Harvey the rabbit of Jimmy Stewart movie fame) other Phookas are blood-thirsty vampire-like creatures which lure humans to their doom.
Indian mermaid art by Eva Campbell
A heraldic monster of myth, the Yale was first spoken of by Pliny the Elder; it was an antelope-like beast about the size of a horse with tusks, long horns, and the tail of a lion or goat. Apparently it enjoyed wallowing in water. In battle, both horns could be used at once to meet aggression from any direction.