First of all the Loreley is a German Myth and because of that probably not well-known to everyone. So I think this concept is very unique, isn't it ?
The most famous one is the one about a beautiful maiden who distracts the sailormen and makes them fall for her, so their ships crash against the rock. She's quite often called a witch for this special power or equalized with the greek sirens.
But the Loreley isn't just a bad siren out of nothing ! She was deeply in love with a faithless man and committed suicide by throwing herself into the river. So she was transformed into this luring woman, who is seducive and passionate. She's combing her long blonde hair and sings all day to make the sailormen suffer and feel her rage about beeing cheated on.
The myth became popular because of a poem by the German poet Heinrich Heine. Here's a somehow translated and very similar version in English by Mark Twain.
An ancient legend of the Rhine
I cannot divine what it meaneth,
This haunting nameless pain:
A tale of the bygone ages
Keeps brooding through my brain:
The faint air cools in the gloaming,
And peaceful flows the Rhine,
The thirsty summits are drinking
The sunset's flooding wine;
The loveliest maiden is sitting
High-throned in yon blue air,
Her golden jewels are shining,
She combs her golden hair;.
She combs with comb that is golden,
And sings a weird refrain
That steeps in a deadly enchantment
The listener's ravished brain:
The doomed in his drifting shallop,
Is tranced with the sad sweet tone,
He sees not the yawing breakers,
He sees but the maid alone:
The pitiless billwos engulf him!-
So perish sailor and bark;
And this, with her baleful singing,
Is the Lorelei's gruesome work.
