Ra Devil (ラーデビル, Raa Debiru?) is the leader of the Black Moon and main antagonist of Final Fantasy: Legend of the Crystals. Robotic to a certain degree, he is determined to have godlike powers. Ra Devil is trying to steal the four crystals and has taken Cid's brain to further his goals.
Before the actual events of the story, Ra Devil stole Cid's brain from his grave since it was the only thing left in the world with knowledge of the crystals. However, Cid's grandson Mid, who was there grieving, caught Ra Devil defiling his grandfather's grave so Ra Devil shot him through the heart, killing him instantly. Ra Devil used the knowledge from Cid's brain and used it to steal the Fire, Water, and Earth crystals and now has his eyes set on the Wind crystal, his ultimate goal to become the God of oblivion known as Deathgyunos.
When the heroes figure out that Ra Devil is after the Wind crystal, which is currently residing within Linaly, they decide to travel to the Black Moon and stop him. Realizing that the only way to get to the Black Moon is with a wind drake, they race to the spire where the wind drakes reside, only to be attacked by Ra Devil's robotic forces on the way. At the tower, Ra Devil constructs a monster out of stone and kidnaps Linaly to the Black Moon, with the party taking the Wind Drake to rescue her.
On the black moon, Ra Devil uses the power of the crystals to become Deathgyunos, a horrible abomination that wants to destroy the world. After a constant barrage of attacks, Deathgyunos is defeated not once, but twice. Ra Devil rises from the rubble of the God and attempts to kill Prettz; however he fails and is sliced in half before erupting in an explosion.