Lamia

The lamia is a, most commonly, female creature with several very different forms across several mythologies. One form is that a beautiful daemon who eats children. Another form has the lower body of a beast, often lions, goats or snakes, and the head, arms and torso of a human, sometimes covered in snake scales. Yet another form is that of a female river spirit who helps the locals in return for food. Lastly, the name lamia, can also apply to swarms of sentient insects inhabbiting the corpses of fey creatures.

Source
The lamia originates from Greek mythology, dating back to at least 400 BC. The water spirit appears as an apparently unrelated being in Basque mythology.

Media
Lamiae appear in the following media:

Movies

 * Drag Me to Hell (2009)

Music

 * The Lamia appears as a track on The Lamb Lies Down on Broadway by Genesis.

Novels

 * Night Music: Nocturnes Volume 2