"Do not fear Kratos. I am the Oracle of Athens, here to help you defeat Ares. Find my temple to the east, and I will show you how to murder a god." - The Oracle of Athens
At the ancient Greek city of Delphi, there was a priestess known as the Oracle. Many people would consult her for various information.
In God of War
In God of War there is apparantly an Oracle of Athens. When Kratos saves her from falling to her death, she looks into his mind to see the man he truly is. With that, she is horrified at how he came to power and can't believe that he's the one who Athena sent to save the city. Nonetheless, she then tells him how he must obtain Pandora's Box if he is to defeat Ares. Upon returning to Athens from the Underworld, Kratos soon finds the Oracle badly wounded. In her dieing breaths, she tells Kratos that Ares had taken the city.