Mad King may refer to:
- Ashnard, the king of Daein and the main antagonist in Fire Emblem: Path of Radiance.
- The Mad King's War, the event of the war of Daein and Crimea during in Fire Emblem: Path of Radiance.
- Gangrel, the king of Plegia and the major antagonist in Fire Emblem Awakening.
- Mad King Gangrel, the eleventh chapter of Fire Emblem Awakening.