In God of War: Ghost of Sparta, Kratos's mother is named Callisto.
Callisto appears during Kratos's journey through Atlantis, where he seeks answers about his family and the disappearance of his brother, Deimos. She reveals that Deimos was taken because of a prophecy concerning a marked warrior, helping explain the events that shaped Kratos's life before the original God of War.
Callisto is not the same character as Lysandra, Kratos's wife, or Athena, the goddess who frequently guides him. Her role is specific to the backstory explored in Ghost of Sparta, the 2010 PlayStation Portable prequel developed by Ready at Dawn.
The game expands the series' Greek-era mythology by showing previously unseen parts of Kratos's past. Its story takes place after Chains of Olympus and before the original God of War, making Callisto's revelation an important bridge between the prequel narrative and Kratos's established history.