The monstrous creature in Greek mythology born from the blood of Uranus is the Furies (or Erinyes). Representing vengeance, they emerge from the castration of Uranus by his son Cronus, symbolizing the retribution for bloodshed and moral transgressions. The Furies personify the darker aspects of justice, haunting wrongdoers and serving as a reminder of the consequences of one’s actions. Their existence highlights themes of guilt and the need for atonement in the human experience.