The Legend of the Black Freighter: dreamed of by a serving girl in a tavern. One day it will come, level the tavern and its obnoxious clientele if not the whole town. and then declare the serving girl Pirate Queen and sail over the horizon with her.
In Greek mythology, the sirens were dangerous and beautiful creatures, portrayed as femmes fatales who lured nearby sailors with their enchanting music and voices to shipwreck on the rocky coast of their island.
A Siren isn't really a sea monster but sailors have told tales of these beautiful women that sing to you and seduce you into their trap of bloodlust. They are said to eat the sailors alive or drowned them deep in the ocean.
"Mermaid" My favorite stories about mermaids and sirens often include bewitching unwitting sailors to their deaths. I have absolutely nothing against The Little Mermaid but sometimes a darker fantasy is really all I want to read.