Siren Painter. Odysseus and the Sirens. Photograph of pottery.<http://en.wikipedia.org/wiki/Siren_(mythology)>
Name: The Sirens
What it is: A siren is a creature with the head of a woman and the body of a bird, a hideous monster if not under their spell but a magnificent creature when trapped in the web of their song.
Crimes: Hypnotized (and hypnotizes) passing sailors to crash their ships among the spiky rocks surrounding their home.
Last seen: Three rocky islands called Sirenum Scopuli, with beautiful meadows and forests, but surrounded by deadly, sharp rocks.
Caution: Their song is so beautiful and hypnotizing it forces you to sail into their islands' rocks of death.
Weaknesses: Ignorance of their song or their victims being too far to hear.
Reward: Safety of you, your sailors, your ship, and your life.
Update: Odysseus and his sailors, after successfully passing the sirens, have guaranteed that stopping your ears with wax, as well as tying yourself to the mast,can prevent hypnotism, although tying yourself up can result in bleeding, rope burn, and rashes from yanking, pulling, and straining.