Cu Sith
 

The Cu Sìth or Cusìth of Scottish mythology (pronounced 'coo shee') is an enormous, otherworldly hound, said to haunt the Scottish Highlands. Roughly the size of a cow or large calf, the Cu Sìth was said to be dark green in color with shaggy fur and a long braided or curled tail.

Legend has it that the creature was capable of hunting silently, but would occasionally let out three terrifying barks that could be heard for long distances, including by ships at sea. This was said to be a warning to farmers to lock up their women, lest the beast abduct them and take them to a fairy mound (Scottish Gaelic, sìthean ) to supply milk for fairy (daoine-sìth) children.

Cu Sìth literally means 'fairy dog.' Supernatural dogs in Celtic mythos are usually completely black, or white with red ears. The Cu Sìth's coloration is therefore highly unusual, although it may be derived from the green color often worn by Celtic fairies.