Selkie
Way up north, sitting by the sea, looking at seals all day, who could honestly say they haven’t had at least one romantic thought about those little water-dwelling blubber-bags? The story of the Selkie is the story of that love that dare not speak its name (basically).
In the folk tales of Ireland, Scotland, Iceland, and the Faroe Islands the Selkie pops up from time to time; maintaining the form of a seal while in the water, the Selkies can come ashore, shed their skin, and take the form of a beautiful human. Nearly every story involving a Selkie is a romantic tragedy of some sort, whether it’s that of a beautiful lady Selkie tricking a sad farmer boy into the water to smash him up on rocks, or a guy with nothing better to do stealing the shed sealskin of a Selkie maiden and forcing her to marry him, the tales generally aren’t “feel-good.”
The males of the supernatural species spend most of time seeking out women who are angry or dissatisfied with their husbands and seducing them; their homewrecking abilities are unquestioned.
The leading theory on where the Selkies come from, regardless of what they do, is that they are the bizarre reincarnation of restless drowned souls.