Arch Demon may refer to:
- The enemy from Final Fantasy XI.
- The enemy and genus from Final Fantasy XIV.
- The enemy from Final Fantasy: The 4 Heroes of Light.
The prefix arch-, as in "archangel" or "archvillain," comes from Greek arkhos meaning "most important."
demon is "an evil spirit or devil, especially one thought to possess a person or act as a tormentor in hell."A