Sthenno, Whose name means "The Strong One" or "Strength", is one of the three sister Gorgones, terrible monsters of Greek myth. She is sister to Euryale ("Wide-Stepping" or "Wide Salt Sea") and the famous Medusa, ("Queen" or "Mistress"), the only one of the three Who was mortal. The death of Medusa at the hands of Perseus was a favorite subject of early Greek vase painting, and on these vases Sthenno and Euryale are typically shown giving chase to Perseus, who has just killed Medusa and is making off with Her head in a bag.

The medium is watercolor pencil.