Alien races from the Godzilla films

The following is a list of the various alien races seen in the Godzilla films.

Xians

Hailing from the mysterious Planet X (located behind Jupiter), the Xians pleaded for assistance from the people of Earth, as it seemed King Ghidorah, having been driven off Earth the previous year by Godzilla, Rodan, and Mothra, was now assaulting their planet. Mankind allowed the Xians to "borrow" Godzilla and Rodan, and The Two monsters were transported to Planet X and were successful in driving Ghidorah away. However, shortly after this the Xians revealed their true colors, and revealed that they had complete control over Godzilla, Rodan, and Ghidorah. They gave humanity twenty four hours to choose between surrendering themselves to Planet X, or being destroyed by the monsters. They finally tired of waiting for an answer and unleashed all three kaiju upon Japan.

Water is very scarce on Planet X and is highly coveted by the Xians, and this was the main reason behind their invasion of Earth. The Xians were vulnerable to loud, high-pitched sounds, and humanity used this to defeat them.

The Xians were a completely emotionless race, letting their lives be run by computers. Their leader is known as the Controller. Everything on Planet X is numbered, according to the Controller, and King Ghidorah was known as Monster Zero. When the Xians gained control of Godzilla and Rodan, they were known as Monster Zero-One, and Monster Zero-Two.

The Xians' spacecraft were capable of traveling one tenth the speed of light, and could fire explosive laser beams from the domes on their underside. Their ships could also encase targets as big as kaiju inside giant force-bubbles, then use tractor beams to haul them great distances, even from Earth to Planet X. They also possessed laser pistols that were capable of disintegrating a human being. Their greatest power, however, had to be their ability to take control of any creature's mind; they did this to Godzilla, Rodan, and King Ghidorah.

Updated versions of the Xians later appeared in the 50th Anniversary film Godzilla: Final Wars.

These Xians contained a special DNA compound called M-Base which they also share with the mutants after breeding with humans 12,000 years ago and in the kaiju, most likely they had altered their DNA. The Sharing of M-Base is what allows a Keizer, a extremely powerful being with M-Base, to control the kaiju and mutants. The lead Xian is a Keizer and so is the mutant character Ozaki, in his case allowing him to resist Xian control. Other then mind control, Xians also are extremely athletic and can fly and teleport and the Keizer Xian himself has telekinetic abilities and can shoot lightning from his hands. Instead of water as their motivation to invade the Earth, they needed the mitrochondria in human cells to survive and plan to farm humans like cattle.

At first they acted as friends, beaming up the 7 rampaging monsters that attacked around the world including Anguirus in Shanghai, Rodan in New York, King Seesar in Okinawa, Kamacuras in Paris, Kumonga in Arizona, Zilla in Sydney and Ebirah in Tokai. After doing so, they propose an alliance with the Earth and renaming the United Nations the Space Nations. They also warn of the giant asteroid Gorath and tell us to fire all our weapons at it.

But peace was not to be, and they actually planned to replace important human leaders with alien clones to convince the people of Earth to trust them. Their cover is blown when Gorath is revealed to be merely a hologram, and the alien clone of the United Nations General is shot and the true form of the Xians is revealed. The Keizer Xian then releases the kaiju, which now include Gigan and Hedorah, to destroy the Earth's cities and defenses such as giant flying battleships and the crew of the Gotengo, the greatest of the Earth's battleships, has to resort to freeing Godzilla, who the Xians weren't aware of, from his Antarctic prison to defeat all the monsters while the Gotengo infiltrates the enormous Xian mothership and defeat the Keizer Xian and his guards. The plan succeeds with the Xians all killed and the mothership destroyed in a massive explosion from the fighting between Godzilla and the Xian's top monster, Monster X. However, before dying, the Keizer Xian gave his energy to Monster X, allowing him to transform into Keizer Ghidorah who nearly kills Godzilla with his levitating gravity beams and energy absorbing bite, though this is put to an end when Ozaki gives Godzilla some of his energy which gives Godzilla the strength and power to kill Keizer Ghidorah with a extremely powerful atomic beam.

Kilaaks

The Kilaaks were a race of female humanoids from the planet of the same, which was said to be between Mars and Jupiter. Setting up bases on both the moon and Earth, the Kilaaks invaded Monsterland and assumed control of the kaiju and resident scientists. Soon the monsters were attacking cities across the globe - Godzilla attacked New York, Rodan assaulted Moscow, Mothra invaded Beijing, Manda attacked London, and Gorosaurus destroyed Paris. Despite the military's efforts to stop them, the Kilaaks remained unscathed until their base on the moon was destroyed by the rocketship, Moonlight SY-3. When humanity broke the kaiju from their control, the Kilaaks pulled out their trump card - King Ghidorah. However, up against the combined might of Godzilla, Anguirus, Gorosaurus, Rodan, Mothra, Kumonga, and Minya, Ghidorah was easily slain. Godzilla then destroyed the Kilaaks' base on Earth, ending their threat.

Unlike most of the other alien races seen in the Godzilla series, the Kilaaks don't seem to have a reason for conquering the Earth, other than Causing death and destruction everywhere. The Kilaaks thrived in high temperatures and were greatly succeptible to cold. When they were struck by low temperatures, they shed their human guises and reverted to their true forms: small, metallic snake-like creatures.

Aside from their mind control devices (that can enslave both humans and kaiju alike), they don't seem to have any great technology, though they do have forcefields that can't be penetrated even by bullets. Their flying saucers aren't much of a threat in and of themselves, but they have the ability to engulf their outer hulls in flames, burning anything the ship may touch. This mode is called a "Fire Dragon."

Nebulans

The Nebulans invaded Earth in order to escape their own dying planet, located in the Star Hunter M Nebula. Using "action signal tapes" to control Gigan and King Ghidorah, the Nebulans had the two monsters demolish Tokyo until they were challenged by Godzilla and Anguirus. The Nebulans were headquartered in a large Godzilla-shaped structure called the Godzilla Tower. The Tower was capable of firing lethal laser beams from its mouth, and these beams very nearly killed Godzilla until the Tower was destroyed by explosives planted in the head, freeing Gigan and Ghidorah in the process.

The Nebulans called their human guises "uniform," and could only use previously deceased humans for them. When their uniforms were killed (or perhaps simply sustained enough damage), the Nebulans would shed their uniform to reveal their true forms: massive, human-sized cockroaches.

With the exception of the Godzilla Tower, the Nebulans possessed nothing impressive, and after their initial invasion, were never heard from again, except to send Gigan to assist Megalon in Godzilla vs Megalon (1973).

Simeons

Simeons were humanoids that hailed from the "Third Planet from the Black Hole," planning to conquer the Earth and settle in before their own homeworld was sucked into oblivion by a nearby black hole. Their greatest weapon was the Mechagodzilla, a mechanical version of Godzilla. At first disguised in a fake Godzilla skin, Mechagodzilla attacked Japan (badly injuring Anguirus in the process) until it was challenged by the real thing. Remotely shedding Mechagodzilla's skin, the Simeons had the robot unleash its fury onto Godzilla, and the ensuing fight resulted in a double knock out. Recalling Mechagodzilla back to their base for repairs, the Simeons were also trying to steal the statue of King Caesar, an ancient daikaiju god, who they did not want to awaken. Though Mechagodzilla was eventually repaired, they failed in stealing the statue, and King Caesar rose, and was soon joined by Godzilla. Both monsters were very nearly killed by Mechagodzilla, but the machine finally met its match when Godzilla revealed a new magnetic power of his, twisting Mechagodzilla's head off. The Simeons were killed when a malfunctioning computer caused their base to explode.

The Simeons returned the next year with a rebuilt Mechagodzilla, and this time they joined forces with a vengeful scientist that controlled the dinosaur Titanosaurus. The Simeons didn't really care for the scientist, and merely saw Titanosaurus as a way to weaken Godzilla before he faced Mechagodzilla. Mechagodzilla and Titanosaurus attacked Tokyo, and were faced with Godzilla. After a long, long fight, Godzilla eventually triumphed over both foes, burrying Mechagodzilla in a giant chasm and seemingly [...] Titanosaurus. The Simeons tried to escape in their spacecraft, but they were blown out of the sky by Godzilla. Any remaining Simeons were killed by the military.

Like the Nebulans, the Simeons didn't seem to possess any impressive technology other than their ability to construct Mechagodzilla. The Simeons were extremely arrogant, acting as if they were invincible until the very end. Also like the Nebulans (and the Kilaaks), the Simeons' human appearance was merely a disguise - when injured or killed, the Simeons (or at least the wounded part of their body) would revert to their original form: humanoid apes with green skin.