The Lunarians (月の民, Tsuki no tami?, lit. "Moon People") are a race of moon inhabitants from Final Fantasy IV. Many years prior to the events of the game, they lived on a planet between the "Red Planet" (Mars) and the "Great Behemoth" (Jupiter).
Physically, Lunarians appear nearly identical to humans, but are very long-lived. People of Lunarian heritage seen in Final Fantasy IV possess no distinctive physical traits that would identify them, other than their light-colored hair, which most Lunarians seem to possess.
Lunarians are natural mages, and most of them seen in the games know the ultimate magic, Meteor, along with a variety of other high-level spells.
The Lunarians' planet was about to be destroyed, so they fled and came to the "Blue Planet" (Earth). They discovered that the humans were still in the process of evolution, and at the moment they could not co-exist. The Lunarians decided to await the day the humans could understand and live peacefully with them, so a second moon was created in orbit over the planet.
Eight of the sixteen Crystals the Lunarians possessed were taken to Earth, presumably to either speed up the evolution of the humans, or to harmonize the Red Moon with the planet to stabilize its orbit. The Lunarians went to sleep near the moon's core, while one of them, Fusoya, stood guard over them. The only entrance to the path to the core was concealed underneath the Crystal Palace.
Although the majority of Lunarians were content to sleep and co-exist with humans, Zemus believed they should use the Giant of Babil to destroy humanity and leave Earth to the Lunarians. It is for this reason, as well as the protection of the Lunarians as a whole, that Fusoya sealed Zemus and forced him to sleep.
Fusoya's brother, Kluya, eventually built an airship known as the Lunar Whale to travel to Earth where he taught advanced technology such as airship building and the Devil's Road, and the secret of magic. Kluya also fathered two sons with a woman named Cecilia. Kluya was eventually killed by a group of "angry humans" and his spirit came to rest atop Mount Ordeals. The orphaned Theodor abandoned his baby brother Cecil at Baron, where he would be taken in by the King of Baron. Theodor was contacted telepathically be Zemus, who still possessed psychic powers in his sleep, and eventually Zemus took control of Theodor's mind, christening him Golbez, "an insect birthed from womb of dragon's corpse".
Under Zemus's control, Golbez gathers the eight Crystals of Earth and activates the planetary elevator within the Tower of Babil, transporting the Giant of Babil to Earth. Through the combined efforts of Cecil Harvey and his allies, the Giant is destroyed and Golbez is freed from Zemus's control. Golbez returns to the moon with Fusoya, intent on killing Zemus.
Confronting him in the moon's core, the two are able to kill Zemus, but his hatred survives and develops a consciousness of its own, becoming the beast Zeromus. After Zeromus is defeated, the Lunarians decide the Earth would be better off without their presence, and make their moon move out of Earth's orbit, heading for parts unknown.
In Final Fantasy IV: The After Years, the moon is targeted by The Creator for their Crystals. Fusoya and Golbez must fight Maenad, who revives Zeromus to attack them. Golbez manages to escape to Earth, but Fusoya remains behind as Zeromus uses his Big Bang attack. Golbez is teleported aboard the Lunar Whale and sent to Earth. The fate of Fusoya and the Lunarians after this is unknown, though Golbez mentions in the ending he plans to return to the moon and find out.