In Greek mythology, Kratos, also known as Cratus or Cratos, is the divine personification of strength. He is the son of Pallas and Styx. Kratos and his siblings Nike ('Victory'), Bia ('Force'), and Zelus ('Glory') are all the personification of a specific trait. Kratos is first mentioned alongside his siblings in Hesiod's Theogony. According to Hesiod, Kratos and his siblings dwell with Zeus because their mother Styx came to him first to request a position in his regime, so he honored her and her children with exalted positions. Kratos and his sister Bia are best known for their appearance in the opening scene of Aeschylus' Prometheus Bound. Acting as agents of Zeus, they lead the captive Titan Prometheus on stage. Kratos compels the mild-mannered blacksmith god Hephaestus to chain Prometheus to a rock as punishment for his theft of fire.

In Greek mythology, Styx, also called the River Styx, is a goddess and river of the Underworld. Her parents were the Titans Oceanus and Tethys, and she was the wife of the Titan Pallas, and the mother of Zelus, Nike, Kratos, and Bia. She sided with Zeus in his war against the Titans, and because of this, to honor her, Zeus decreed that the solemn oaths of the gods be sworn by the water of Styx.