Mélusine is a character who frequently appears in the legends and folklore of medieval Europe, and is generally portrayed as half-woman and half-fish. In that she, of course, resembles a mermaid, but the difference is that she is linked to fresh, rather than salt water, and tends to be associated with wells and rivers. In some depictions, she also has wings.

Legends about her are most frequent in Germany, France, Luxembourg, and Great Britain, though the figure appears all over the continent and features in the medieval epics of several languages and civilisations.

An interesting thing about Mélusine is that she has, to some extent, crossed the boundaries between folklore and actual chronicled history. The Plantaganets, in particular, believed that they were descended from her.

Like many mythical figures, she has inspired writers and artists throughout the centuries, and has featured in works as diverse as operas by Dvorak and Reimann, J.K. Rowling's "The Beasts of Grindelwald", and video games ... and the logo of the Starbucks coffee company is believed to be based on her!

More Info: en.wikipedia.org