The Drej are a race of malevolent energy-based aliens and the central antagonists of Don Bluth's 10th and final animated feature film Titan A.E.. They despise humanity due to an expermental discovery called “Project Titan”, which alarmed them due to the power it would have allowed humanity to possess. Terrified that humanity would use their new power to "dethrone" them or otherwise threaten them as the most powerful species, the Drej declared war, and they intend to get rid of all humans from the universe, in order to be the only dominant species in the galaxy.
The prologue of this movie is set in the year 3028 AD, then flashes forward 15 years to the year 3043. The film focuses around a young man named Cale Tucker, and a special ship called the Titan. In 3028, Earth is destroyed by the Drej, a malicious race of aliens that are made of pure energy. The ship in which they travel is called the Alahenena, supposedly the Drej language term for planet killer. This ship positions itself over the North Pole of Earth and fires an energy beam at it, causing the planet to spin faster and faster, until centrifugal force overpowers gravity, thus causing Earth to fly apart at the seams.
Not much is known about the Drej, other than the fact that their social structure is much like that of bees, with a queen and several armies of drones. One thing to notice about the Drej is that the queen is the only one who has eyes; the rest are eyeless drones.
The Drej have two primary modes of transportation; the large mothership called the Alahenena supposedly the Drej language term for “planet killer”, and swarm upon swarm of smaller ships called Stingers. The Stingers are very aggressive looking; a small central fuselage with a pair of sharp fins on the back and another pair on the sides, and a pair of long arms coming up at an angle from the sides, then leveling off, and coming back down at a slight angle inward toward each other. After Cale was taken prisoner aboard the Drej mothership, he managed to escape and steal a Stinger, which he then flew back to the starship Valkyrie. Captain Joe Korso and his crew did not know that our hero was aboard the Drej Stinger; Stith fired a few shots, which Cale manage to dodge by manipulating bolts of energy on the ship's seat. The starship Valkyrie picked up the stolen Stinger, and Mr. Tucker dropped out of the bottom of the ship.
The Drej are not much different from our species, yet they are made of bright blue pulsing energy. They're not corporeal entities, yet they have a physical form which appears to be both skeletial and humanoid. Their ships are also made of energy, a fact that young Mr. Tucker exploited. You won't need a dictionary to know that the Drej were victims of bad karma. Mr. Tucker reconfigured the Titan's systems to use that very energy from which are Drej are made; they and their ship and their queen were absorbed into the interior of the starship Titan, and as she awakened from her 15 years slumber, she unleashed that energy in three violent bursts. These bursts created three beams, each long enough to span a planetary radius. This created a gravity well, which caused all material around the Titan's position to coalesce into a hot clump of molten matter, thus giving new life to a planet upon which the human species could live.