Hades is the ruler of the mythological underworld in Greek mythology. In ancient Greek religion and mythology, Hades was the god of the dead and the king of the underworld, a dark and gloomy place where souls of the deceased would go after death.
Note: The provided meaning of the answer is for the latest New York Times crossword puzzle clue: Ruler of a mythological underworld. Explanations are generated by AI and may be inaccurate.