Cu Sith/Cusith

Cù Sìth also Cusìth are large hounds from the fae realm close to the size of a large calf, with dark green or black, shaggy fur, glowing or flaming eyes, and a long braided or curled tail.  They are believed to be a harbinger of death when seen in the wild, and are commonly owned as guard dogs and pets.  Their fearsome reputation is often fostered by those who own them.