The Head of Medusa. To find out more about Medusa, see this Wikipedia article: link; for information about the image: image source.
The famous image by Caravaggio shows the severed head of Medusa, complete with dripping blood. Medusa seems rather surprised by what has happened in fact - more terrified than terrifying. You can read the details about just how Perseus managed to behead this monster in Wikipedia.
You can also find more myths and legends for the week of February 12-18 here. For more information and links to the actual javascript code, see the Myths & Legends Widget Reference Page.