The Luminoth is a species found in the GameCube video game Metroid Prime 2: Echoes. They are an advanced species who for years traveled the galaxy, finally deciding to make their new home on the planet Aether after being influenced by the Chozo. Apparently the two peaceful species met each other on an occasion, in which they traded knowledge and technology which would benefit each other.
They lived happily on their new planet, until a meteorite from Phazee crashed onto Aether, thus generating a mysterious new dimension that was later titled Dark Aether, which would in time cause panic among all the inhabitants of the planet once creatures started to imerge from the opposing world via dimensional rifts that were, too, created. The creatures, known as Ing, thankfully evaporated into thin air, though not for long.
Not only that, but the meteorite also caused Phazon to spread throughout the planet. To make matters worse, there is a new enemy that has landed on Aether and its name is Dark Samus,a dark version of Samus. The creatures mentioned above eventually found ways to survive the light world, and started to possess many of its inhabitants including some of the Luminoth. Most of the surviving Luminoth, including U-Mos, escaped into the Great Temple, where they were put to sleep until one hopeful day that everything would be restored. U-Mos stayed awake in case any potential threat would arrive, though survival of the species seemed bleak. That is, until Samus Aran arrived on the planet to investigate a missing Galactic Federation ship.
Once the heroic heroine arrived on the planet, she agreed to help restore the power to the Luminoth, and once she did, the species was then capable of defeating the Ing and Dark Samus, and today live peacefully together on Aether thanks to Samus Aran.
The Luminoth have been reported to have lived up to 1,000 years old, meaning the most notable of all Luminoth in the game U-Mos, who is apparently only 200 years old, is still relatively young compared to many of the others.
It has been suggested that the Luminoth created the Screw Attack rather than the previously assumed Chozo, as found through in-game evidence, and that during the two species meeting each other, the Luminoth gave the Chozo the design, as the Chozo gave the Luminoth multiple other inventions.
Super Smash Bros. series
In Super Smash Bros. Brawl, the Luminoth appeared in the form of a trophy and a sticker.
"A creature of the native race of the planet Aether. The Luminoth develop facilities to draw the dwindling energy from the core of their planet. However, they lose that energy when the planet is hit by a Phazon meteor and they are attacked by a race of dark creatures, the Ing. A war over Aether's energy then rages between the Luminoth and Ing races."