Here's my piece of work for the competition. He's a merman that lurks under harbours waiting for unsuspecting victims before dragging them underwater and eating them. Th best way to get into a merman's favour (and thus saving yourself) is to give them jewellery; they love the stuff, but they do have a habit of eating people they like or you know, biting them in ways that creepy fans consider seductive when really they're finding out whether you taste any good.
They have an overwhelmingly beautiful voice and can get you to do whatever they please once you've caught them singing; it's unavoidable, which is why the hunters often have ear plugs.