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For other things that refers to the concept of being an Impostor, see Impostor (disambiguation).

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Surprise Motherf*ckers!

—Xenomorph as Brown Crewmate

The Alien (also known as Xenomorph, Internecivus raptus or Imposter) is a minor character in the SMG4 series.

It is a fictional endoparasitoid extraterrestrial species that is the eponymous antagonist of the popular Alien film series. It appears in various videos, usually as an antagonist.


The Xenomorph can take on many forms, but seems to have common traits, including an inner jaw, a long tail with a sharpened edge, a eyeless elongated head, and acid blood. Commonly, they start out as embryos, which are carried by a Facehugger, hand like creature with 8 legs, a tail, and a mouth on its belly, which it uses to impregnate a host. Facehuggers are usually contained in eggs, human-sized egg like structures with a 4 way opening. After a period ranging from 10 minutes to 6 hours, the Chestburster, a small, snake like creature with similar features to an adult Xenomorph, emerges from the host chest. In cases where there is no queen present, a Xenomorph may become a queen, a larger variant of the Xenomorph with 4 arms, a crown like appendage piercing out of the back of it's head, and a detachable sack, used to reproduce and create more eggs. The variants seen in the episodes seems to be a normal Xenomorph warrior or drone, but unlike other Xenomorphs, some holding a crowbar and can speak, showing a higher level of intelligence than average.


It can be presumed that each Xenomorph is no different from the others, intending to kill anything that proves a threat. However in SMG4: The Movie Audition and SMG4: Mario Raids Area 51 instead of using its natural weapons, Drone Xenomorph and Grid use a crowbar. This could mean they might be smarter than other Xenomorphs.

The one shown in SMG4: If Mario Was AMONG US... is manipulative, framing two other Crewmates (Blue Crewmate and Red Crewmate) for the murders it committed.


SMG4: The Movie Audition

When Steve re-enacted the role of Forrest Gump and quoted the line, "Life is like a box of chocolates.", an Xenomorph popped out of the box and roared in rage before attacking the Koopa Troopa, seemingly killing him, whilst Steve admires the Troopa's shoes.

SMG4: Mario Raids Area 51

Another Xenomorph, Grid, appears in the episode. However, Mario shot at it.

SMG4: Wario Tries To Stop Himself From Dying

A drone Xenomorph returns in the episode as the reason why the Wario Bros Residence's toilet was clogged.

SMG4: Mario The Supreme Leader

A chestburster-sized Xenomorph appears when it burst out of Mario's chest after Mario tested the lake's water's contamination (which was caused by Donkey Kong defecating in it) by drinking it. Mario though was unfazed by the damage it did to him and threw the Xenomorph back into the lake where it presumably drowned.

SMG4: If Mario Was AMONG US...

It is the main antagonist although most of its appearance in the episode is a brown crewmember. It attacked and killed the Crewmates while they were attempting to repair Peach's Castle, and also manipulated Crewmates into killing each other. It is eventually discovered as the impostor (as Mario realized that it had been spying on them from the vents, which a crewmate cannot enter) and after it chased the two remaining survivors, it is tricked by Mario, shot by the Green Crewmate, and is thrown into space.

SMG4: The Fan Written Episode (4 Mill Sub Special)

In the episode, it is once again an impostor under Swagmaster's disguise and tried to turn some people into spaghetti. FM tried to incapacitate him but it was Mario who did most of the job to reveal him by kicking Bowser's crotch in order for him to spit fire at the Xenomorph. This caused its disguise to fail revealing to everyone that he was an impostor. During the fight, Mario sold his soul to FM who gave it to Cube in order to turn him into a robotic giant. Cube managed to kill the alien impostor easily.

SMG4: Mario goes to the Dentist...

In the episode, Tari accidentally ate it, causing Mario, under his Dr. Mario persona, to remove it. The Xenomorph then kidnapped a baby Yoshi before fleeing to Mexcio.


Mario Plays: Deltarune

Xenomorph is briefly shown when Mario calls one of the characters "Xenomorph's mom".

Criminal Record


  • The fact that in SMG4: If Mario Was AMONG US... he is the impostor is a reference to the fact that in the actual game, the impostor is supposed to be an parasitic alien that can shapeshift into a crewmate.
  • James Bailey, the voice actor who portrayed him in SMG4: If Mario Was AMONG US... voices the main villain of SMG4, SMG3.
  • The Metroids from the video game franchise Metroid are very similar to Xenomorphs, right down to the Metroid Queen and Xenomorph Queen.


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