In Egyptian mythology, the goddess of truth and justice is Ma'at.
Ma'at was both a goddess and the principle of truth, balance, order, morality, and justice. Ancient Egyptians believed that she helped regulate the cosmos, including the stars, seasons, society, and the conduct of gods and humans. Her opposite was Isfet, associated with chaos, violence, falsehood, and disorder.
Ma'at is usually shown as a woman wearing an ostrich feather, her defining emblem. Egyptian kings were expected to uphold Ma'at through just government and proper religious rituals. From the Eighteenth Dynasty onward, she was commonly described as the daughter of the sun god Ra.
Her feather played a central role in the afterlife. In the Weighing of the Heart ceremony, a deceased person's heart was measured against the Feather of Ma'at. A worthy heart allowed the soul to enter Aaru, while an unworthy one could be devoured by Ammit. Ma'at is sometimes confused with a mere goddess of law, but her role was much broader: she represented the universal order itself.