The Milennians are an alien species and main antagonist of Godzilla 2000.
Millennian's solar-powered spaceship crashed on Earth during the Cretaceous period, and they remained dormant for ages until drilling operations exposed them to sunlight again, waking the sunken menace. They initially plan to modify Earth's atmosphere to suit their needs as well as giving cryptic message to humanity that they would conquer Earth, but with Godzilla stood on their path and discovered that the kaiju's genetic issues can restore their anti-matter converted bodues, they decide to instead modify themselves using genetic material from the monster, hoping to acquire its regenerative abilities and restore their bodies that reduced into anti-matter.
After some difficulties in incapacitating the kaiju, the ship's crew managed to absorbs and uses Godzilla's genetic samples to restore their bodies, and manifests themselves as a huge tentacle creature somewhat resembling a mixture of jellyfish and mushroom. Though they successfully restore their physical form as a composite creature, something when wrong: As Yuji Shinoda stated, Millennians were overestimate Godzilla' Organized G-1 in his genetic material, and as result, the composite form of Millennians wind up mutate uncontrollably as they helplessly watch their composite body taking some traits of Godzilla, giving rise to the hybrid monster known as Orga that immediately dispatched by Godzilla himself.
While Millennians have malicious intention to conquer Earth, they not dependant upon brute force in doing so, as they seem to want to gather all the information from technology that they can to carry out such task, via telepathy, hacking, and biological information. This is apparent as when they attacked a news building, they hacked every single computer in that building to find out everything on Earth includes Godzilla, whom have Organizer G-1 that they need to restore their bodies. They also seems to not want to fight unless absolutely necessary; even once it has mutated into Orga, it is obvious that it does not want to battle Godzilla until it realizes that escape is not an option.
AppearanceIt's unclear what Millennians'actual form looked like, but at first, it looked like a ball of glowing yellow dust of anti-matter when exit the ship. Then, after absorb enough genetic material from Godzilla, they immediately accessed their composite form that looked like a huge tentacle creature somewhat resembling a mixture of jellyfish and mushroom.