Astos

Astos (アストス Asutosu) was the evil king of the Dark Elves in the original Final Fantasy. He and his cronies attacked Elfheim just before the Warriors of Light arrived, placing a curse on the Prince of Elfheim and sacking the treasury.

Afterwards, he stole Matoya's Crystal Eye to prevent her from making a potion to revive the Prince, and then posed as a weak old king in the Western Keep and tricked the Warriors of Light into recovering the Crown from the dangerous depths of the Marsh Cave. When the Warriors returned, Astos showed his true form.

The Warriors of Light prevailed in battle and defeated Astos.

Battle
Players will have no problem defeating Astos if they considered leveling up a bit in the areas around Elfheim or the Marsh Cave. Physical attackers should do their thing, while Red and White mages should use Heal. Black Mages should use Tier-2 magic such as Firaga, etc., and be sure to have some Phoenix Downs or the spell Life, as Astos has the magic Death, which can instantly KO any character. Be sure to heal constantly, and the victory fanfare should be playing soon enough.

Other Appearances
In the Dawn of Souls remake, Astos appears in the Whisperwind Cove. There is a room with flame-like spirits which must be calmed so they can go rest in peace. One of those souls is Astos, seeking revenge. Another boss battle ensues, but Astos has the same level as before, and as the Light Warriors have grown stronger, Astos can easily be defeated with only one hit. After saying his last words, Astos finally rests in peace.

He (or his name) was also in an episode of Captain N: The Game Master under the disguise as a Friar who had the Light Crystal.

Basis
While decidedly different in appearance, Astos and the other dark elves are based on the drow elves from Dungeons and Dragons.

Astos