Hailing from Planet X located just beyond Jupiter, the Xiliens are a technologically advanced race bent on conquering the Earth for themselves. In Invasion of Astro-Monster, the Xiliens pretended to be under siege by Monster Zero, their name for King Ghidorah, and reached out to humanity for assistance. After humanity allowed them to bring Godzilla and Rodan to Planet X to stop King Ghidorah, they revealed that Ghidorah had been their pawn the entire time and that they now had control over both Godzilla and Rodan. When mankind did not capitulate to their ultimatum that the Earth become a colony of Planet X, they unleashed all three monsters on Earth. However, human scientists were able to defeat the Xiliens using a special sound frequency and invented a device to sever their control over the monsters. Defeated, the Xiliens self-destructed their UFOs and base on Earth.
The Xiliens returned as the villains in Godzilla: Final Wars nearly four decades later. Intending to harvest the mitochondria from human cells for sustenance, they again posed as allies to humanity, unleashing an army of monsters under their control before teleporting them all away. When their plan was exposed by the Earth Defense Force, the Xilien Commander was assassinated and usurped by his subordinate who became the Controller of Planet X. The Controller unleashed all of the Xiliens' mind-controlled kaiju on Earth and tried to eliminate all resistance, but the surviving members of the EDF used the Gotengo to free Godzilla from his prison in Antarctica. Godzilla swiftly eliminated most of the Xiliens' monsters before the Controller summoned his ultimate weapon, Monster X, to stop him. The Gotengo breached the Xilien Mothership and its crew were able to defeat the Controller and his minions. In a final act, the Controller set the Mothership to self-destruct, but the Gotengo was able to escape in time and help Godzilla overcome Monster X's final form, Keizer Ghidorah.
The Xiliens are very popular antagonists in the Godzilla franchise and Toho's most famous alien race, having been featured prominently in films from both the Showa and Millennium series. Outside of their two film appearances, the Xiliens are frequently featured as the villains of various pieces of non-film media. They appear in video games such as Godzilla: Monster of Monsters! and Godzilla Defense Force, and are the recurring antagonists of the 1997 television series Godzilla Island. Additionally, the Xiliens are the inspiration behind the Exif race in the GODZILLA anime trilogy.
The Xiliens are referred to as "X Aliens" (Ｘ星人 in the Japanese dialogue for both Ekkusu Seijin)Invasion of Astro-Monster and Godzilla: Final Wars, referencing the name of their home planet, Planet X. In most Japanese publications, including Godzilla 1954-1999 Super Complete Works, the original Showa incarnations of the Xiliens are given the English name Alien X. The English translation of the video game Godzilla: Monster of Monsters! refers to them as the invaders from Planet X. The Xiliens had no commonly-used official English name prior to Godzilla: Final Wars, but a common nickname for them was Xians. The English dub of Godzilla: Final Wars finally introduced the English name "Xiliens," a combination of "X" and "aliens," which has been subsequently accepted as the aliens' official English name. The name "Xiliens" is also used in the English subtitles for The Criterion Collection's Blu-ray release of Invasion of Astro-Monster. An alternate spelling, Xilians, is seen in the English subtitles for TriStar and Sony's DVD and Blu-ray releases of Godzilla: Final Wars, as well as in concept art for the film. In Invasion of Astro-Monster, the Controller of Planet X tells Kazuo Fuji that he would call his people "Xiliens." In Godzilla: Final Wars, the Xilien Commander states that the name of his race's home planet is impossible for humans to pronounce, and tells humanity to call them "Xiliens."
In Invasion of Astro-Monster, the Xiliens dress distinctly in black and gray vinyl suits. The male Xiliens wear coverings over their heads which cover all except their faces and feature a single antenna on the top and two receivers on each side of their head over their ears. They also wear thin black visors that cover both of their eyes. The female Xiliens all look completely identical, and do not wear any attire over their heads. The Xiliens look like normal humans, however their skin is extremely pale, and they must undergo artificial tanning in order to pass themselves off as humans. One Xilien appears to have metal bolts sticking out of his body when he is tanning, suggesting that the Xiliens are at least partially cybernetic.
In Godzilla: Final Wars, the Xiliens' human-like appearances are simply a ruse. Their true forms are bizarre gray-skinned humanoids with no visible eyes, pointed heads and black veins visible all over their body. When disguising themselves as humans, Xiliens encase themselves in false human skins, which allow them to perfectly imitate human beings aside from the key observation that they do not blink. When an Xilien is killed, the human skin will split open and expose their true forms. When wearing their human skins, most of the Xiliens, including the Controller, dress in blue and black full-body uniforms with long black leather trenchcoats. The Controller himself sometimes wears a black visor over his eyes, a nod to the Xiliens' attire in Invasion of Astro-Monster. The Xilien Commander wears a more distinctive blue and black military uniform which resembles a robe.
In the Showa series, the Xiliens are an emotionless and robotic race. They lack free will and their entire lives are controlled by an advanced computer which is overseen by the Controller of Planet X. Xilien culture is extremely strict and lacks any individuality; all members of the race dress identically while every female Xilien possesses the exact same face which is held as the standard for beauty. Anyone who disobeys the orders of the computer is immediately executed without hesitation. Due to the harsh conditions on Planet X, the Xiliens seek to colonize Earth and plunder its resources. They lack any regard for human life and are willing to completely exterminate the human population if necessary, only granting humanity a window to comply with their demands for convenience. The Controller in particular seems overly confident in his race's machines, basing all of his actions on the computer's calculations and never once doubting that their invasion will succeed.
In the Millennium series, the Xiliens are a highly militaristic culture initially led by the Xilien Commander. In contrast to their Showa incarnation, this version of the race possesses more individuality through the human disguises its members wear. The Commander is very level-headed and shows restraint, attempting to operate in secret to infiltrate humanity and gain its trust so that his people can harvest human mitochondria for sustenance. Once he is usurped and murdered however, he is replaced by the much more violent and impulsive Controller. The Controller views humanity as "cattle" and seeks to use his race's military might to wipe out human civilization and enslave what remains. Under the Controller's leadership, the Xiliens are extremely aggressive and have no regard for human life.
Upon arriving on the newly-discovered Planet X, astronauts Glenn and Fuji encountered the Xiliens, an advanced race of intelligent aliens. The Xiliens' leader, the Controller of Planet X, greeted the two astronauts and informed them that his race had an important request to make of Earth. He explained that Planet X was constantly under attack by a horrible space monster they called Monster Zero, or as the people of Earth knew him, King Ghidorah. The Controller knew that King Ghidorah had been driven away from the Earth before by the combined might of Godzilla and Rodan, and asked to "borrow" the two monsters so they could defeat King Ghidorah again. Glenn and Fuji said they would relay the Xiliens' request to Earth, and returned there aboard their spaceship P-1. While humanity debated whether or not to help the Xiliens, the aliens secretly deployed several of their UFOs to Earth to locate Godzilla and Rodan. The Xiliens finally revealed themselves to the people of Earth, and the Controller arranged a meeting with several Earth leaders. He apologized for operating without permission on Earth, but stressed the importance of their mission. With the permission of the people of Earth, the Xiliens used their UFOs to uncover the locations of both Godzilla and Rodan, then captured them both using anti-gravity technology. The Xiliens then returned to Planet X with the monsters, accompanied by Glenn, Fuji, and their superior Dr. Sakurai. When they arrived on Planet X, Godzilla and Rodan were set free and were immediately attacked by King Ghidorah. Godzilla and Rodan joined forces and quickly repelled King Ghidorah. During the battle, Glenn and Fuji slipped away to investigate Planet X further, skeptical of the Xiliens' true intentions. As they wandered the surrounding area, they encountered two Xilien women, which happened to look identical to Glenn's lover back on Earth, Namikawa. Glenn and Fuji were caught and apprehended by several Xilien guards, then brought back to the Controller. The Controller said that the two astronauts would not be punished, as they were diplomatic guests, but warned them not to cross them in the future. The Controller thanked Glenn, Fuji, and Sakurai for their assistance in making the operation a success, and gave them a tape he said contained the cure for cancer as a reward for Earth's assistance. The three men were sent back to Earth on a replica of the P-1, while Godzilla and Rodan were left behind on Planet X.
When the astronauts returned to Earth and played the tape, they discovered that it contained an ultimatum demanding that the Earth surrender to the Xiliens and become a colony of Planet X. The Xiliens revealed that King Ghidorah was under their control the entire time, and now both Godzilla and Rodan, dubbed Monster Zero-One and Monster Zero-Two, were at their disposal as well. They threatened to unleash all three monster on Earth if humanity did not surrender. In the meantime, inventor Tetsuo Torii had sold his invention, the Lady Guard alarm, to a toy company represented by Namikawa. When the company never paid or contacted Tetsuo afterward, he decided to take matters into his own hands and sneak into the company's office. However, once he arrived he was captured by the Xiliens, who were using the company as a cover for their operations. Tetsuo was thrown into a jail cell while the Xiliens' forces stationed on Earth prepared to launch their invasion. After seeing the Xiliens' women, Glenn came to the conclusion that Namikawa herself was also an Xilien and confronted her. She confessed that she was ordered to pose as Glenn's lover and keep an eye on him, but revealed that she had actually come to love him in that time. She said that the two of them were to return to Planet X together and marry, as the Xiliens' computer had demanded it. Glenn refused to abandon the Earth, and was arrested by some of the Xiliens' soldiers. Namikawa ran to Glenn and slipped a note into his pocket before he was taken away, but was subsequently executed for disobeying orders. Glenn was thrown into the same jail cell as Tetsuo, where he read the note Namikawa had given him. The letter revealed that the Xiliens were vulnerable to a single sound, which Tetsuo realized was the sound produced by his alarm. Having brought the Lady Guard with him, Tetsuo activated it, which incapacitated the Xilien guards. Glenn and Tetsuo took the guards' keys and escaped, then reported their success to Fuji and Dr. Sakurai. Fuji had developed a device that could sever the mind-control waves the Xiliens used to control the monsters, and collaborated with the JSDF to weaponize it as the A-Cycle Light Ray Gun. When the Xiliens grew tired of waiting for mankind's surrender, they unleashed Godzilla, Rodan and King Ghidorah across the globe. With no time to spare, the humanity began broadcasting the Lady Guard's sound on all radio frequencies, which caused havoc with the Xiliens' technology and left them helpless. This allowed the JSDF to turn the tables against the Xiliens and easily damage their hidden base on Earth. As the JSDF assaulted the Xiliens, the A-Cycle Light Ray Guns severed the Xiliens' mind control over the monsters and left them all unconscious on the ground. With the Xiliens' plan a failure, the Controller screamed that they would all escape into the future, then pressed a button that caused all of their UFOs, along with their Earth base, to explode. Once Godzilla and Rodan regained consciousness, they fought King Ghidorah once again and forced him to retreat back into space. At last, humanity was saved from the Xiliens' invasion, while Dr. Sakurai informed Glenn and Fuji that they would be returning to Planet X for diplomatic duties.
In the year 20XX, the Xiliens launched an invasion of Earth, masking their intentions with peaceful purposes. The Xiliens were able to control any lifeform possessing a DNA base known as M-base, and their ability to alter creatures' DNA gave them control over an army of kaiju, which they unleashed across the globe: Rodan in New York, Anguirus in Shanghai, Kamacuras in Paris, Zilla in Sydney, King Caesar in Okinawa, Kumonga in Arizona, and Ebirah in Tokai. After allowing the monsters to wreak havoc, the Xiliens suddenly teleported them all away and revealed themselves to humankind, claiming to have saved them from the monsters. The Xilien Commander and his protege brought the leaders of the Earth Defense Force aboard their Mothership, and claimed that a runaway planet called Gorath was on a collision course with Earth and would destroy it unless they used their superior firepower to destroy it. The Xiliens said they wanted nothing but peace between Earth and their planet, and at their urging the United Nations was reconfigured into the Space Nations. While humanity seemed to embrace the Xiliens, tensions soon arose between the Commander and his apprentice. The younger Xilien believed that they should use their superior weaponry to crush and enslave the human race so they could harvest their mitochondria, but the Commander wanted to perform their purpose on Earth through as peaceful means as possible. In the meantime, Shinichi Ozaki and Miyuki and Anna Otonashi discovered that several high-ranking officials, including the United Nations Secretary General and the EDF's two highest-ranking members, were being replaced by Xilien impostors. They recruited the few EDF members they knew weren't compromised, including Captain Douglas Gordon, then exposed the Xiliens on Anna's talk show by shooting the Secretary General, causing his human disguise to split open and reveal his true colors. The Commander attempted to defuse the situation, but his protege simply laughed and shot the Commander in the head, killing him. He then proclaimed himself the Controller of Planet X and announced his intention to eradicate human civilization and enslave humanity to serve as the Xiliens' cattle. He took control of the EDF's mutant soldiers and set them loose against Ozaki and his allies, then returned to the Xilien Mothership to unleash all the monsters under their command, including the ancient cyborg monster Gigan.
In a short amount of time, major cities around the globe were demolished and the EDF's forces almost completely wiped out. Gordon proposed one last desperate option: amass all of the EDF's remaining forces aboard the Gotengo, then free Godzilla from Area G in Antarctica and allow him to defeat the Xiliens' monsters. The Gotengo was launched and traveled to Antarctica, while the Controller sent Gigan to destroy it. The Gotengo was able to free Godzilla, and he quickly defeated Gigan. Godzilla traveled around the world, defeating each of the Xiliens' monsters one-by-one. After defeating Hedorah and Ebirah in Tokyo Bay, Godzilla reached Tokyo, where the Xilien Mothership was flying overhead. The Gotengo then mounted an assault on the Mothership, and managed to pierce through it. The Xiliens' soldiers however boarded the Gotengo and easily killed all of its crewmembers save for Ozaki, Gordon, Miyuki, and Major Komura. The four of them were taken to the Controller, who taunted them before unleashing his trump card, Monster X, to destroy Godzilla. The Shobijin called on Mothra to aid Godzilla, so the Controller sent the upgraded Gigan to deal with her. The Controller revealed that he and Ozaki were both powerful beings called Keizer, the result of interbreeding between humans and Xiliens thousands of years ago. He used his powers to take control of Ozaki and force him to attack his allies, but Miyuki freed him from the Controller's influence using a sacred dagger given to her by the Shobijin. Ozaki told the others to escape while he fought the Controller. Miyuki, Gordon and Komura managed to free several of the Xiliens' captives, who had ben replaced with Xilien impostors on Earth, then fought through the Xiliens' forces to reach the Gotengo. Ozaki defeated the Controller in combat, but the Controller activated the Mothership's self-destruct sequence, refusing to let Ozaki be victorious. Ozaki ran back to the Gotengo, which escaped just before the Mothership exploded, with the Controller and the rest of the Xiliens' invasion force still aboard. However, while the Xiliens were defeated, one remnant of their invasion still remained: Monster X, who transformed into the more powerful Keizer Ghidorah. Keizer Ghidorah nearly killed Godzilla, but Ozaki used the Gotengo's Maser Cannon to transfer his Keizer energy into Godzilla, allowing him to overpower and finally destroy Keizer Ghidorah.
The Xiliens are a highly advanced civilization far surpassing humanity. In the Showa series, their UFOs are capable of interstellar travel at one-tenth the speed of light, allowing them to quickly and easily travel to and from Planet X. These UFOs are armed with powerful laser guns which can destroy vehicles instantly and melt metal. Some UFOs are equipped with tractor beams and can form an atomic barrier which allows them to easily transport Godzilla and Rodan through space. They also build a superior replica of the humans' P-1 spaceship after analyzing the original model. Because of the harsh surface conditions on Planet X, the Xiliens primarily make their home in a vast underground complex. They are able to access the surface through tubes which serve as elevators. As water is a precious resource on Planet X, the Xiliens must extract and produce it at dihydrogen monoxide plants. The Xiliens speak an alien language, but they have developed a universal translator which allows them to communicate with humans. The Xiliens' most dangerous technology is the electromagnetic waves they can use to control kaiju.
In the Millennium series, the Xiliens are once again highly technologically advanced. They operate primarily from a massive Mothership which itself can deploy Fighters and other UFOs. Their ships are armed with laser cannons that can deal substantial damage to even the Earth Defense Force's advanced vehicles. The Xiliens have harnessed the power of genetic manipulation which they use to alter the genome of Earth's kaiju and gain control over them. Their technology allowed them to create the cybernetic monster Gigan long ago, and in the present day they are able to immediately reactivate him and later upgrade him into a more powerful modified form. Through the use of unknown technology, the Xiliens can flawlessly impersonate any human being. The only fault in their disguises is their inability to blink.
- Godzilla: Monster of Monsters! (1988) - Nintendo Entertainment System / Famicom
- Battle Baseball (1993) - Nintendo Famicom
- Godzilla: Archipelago Shock (1995) - Sega Saturn
- Godzilla: Trading Battle (1998) - Sony PlayStation
- CR Godzilla 3S-T Battle (2006) - Pachinko
- Godzilla: Kaiju Collection (2015) - Android and iOS
- CR True King of the Monsters Godzilla (2018) - pachinko
- Godzilla Defense Force (2019) - Android and iOS
- The Godzilla Comic (1990)
- The Godzilla Comic Raids Again (1991)
- Godzilla: Rage Across Time #5 (2016)
An Xilien pitching in Battle Baseball
This is a list of references for Xiliens. These citations are used to identify the reliable sources on which this article is based. These references appear inside articles in the form of superscript numbers, which look like this: 
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