|Featured in||All missions starting from the 2nd one|
|Role||Close combat strain|
|Speed|| Slow (rookie)|
A Humanoid Alien (Xenorius anthropoeidis), alternatively known as the Extraterrestrial Humanoid or Alien Humanoid, is a common type of the space monsters appeared with the comparable size and characteristics of a human being. Also, it is easily a least powerful creature that has encountered as the first humanoid enemy in the bestiary of the first Space Monsters game and can be found in every mission respectively, except in the first mission of each campaign.
Being teleported from the alien homeworld Xenoria, Humanoid Aliens physically appeared as the bald humanoids to have human characteristics and their bodies are usually shaped similar to humans due to their anatomical differences. For the different skin colors, it appears that each specimen has green for the rookie/normal class, pale brown for the elite class, and gray for the captain class, signified as the army of the extraterrestrial bipeds alongside the other types of aliens than the humanoids, who are under control by both Roki and Syrax respectively in each campaign. Their form of attacking their enemies is slashing, which may be possibly performed by raising up their hands and hitting them in a "karate chop" manner to deal damage at close range. Like any weaker enemies, they can be killed easily by a couple of shots or melee attacks.
When alerted in any corner of the screen, the player will hear one of the four different creature sound effects: a short bark, a ferocious roar, a low cat-like growl or a loud, serpentine hiss in two different pitches. As you can see, the Humanoid Alien acts like a zombie as it walks or runs, getting closer to a playable character, but with human intelligence as an alien feature. The differences of each skin color are their movements. The rookie Humanoid Alien moves slowly while walking. The elite Humanoid Alien walks in a medium manner. And the captain Humanoid Alien moves quickly as it runs on the player. At closed combat, the Humanoid Alien delivers a slashing attack on the player by raising its both hands and doing a "karate chop" motion to damage weakly. It is possibly considered and nominated the third weakest and least dangerous type of enemies in the game, having more health than small creatures, such as Invaderling, vipede, spider, maggot and slug. In order to kill it easily, the player shoots with any gun or effectively use either an explosive weapon (e.g. Grenade Launcher), incendiary device or any energy-loaded weapon against it in ranged combat. Shotgun is another way to get effective against it in close range because of a big damage. For melee combat, the player must hit it with a melee weapon few times for a little while and stay away from the enemy attack until it is killed. After killing it without using any explosive weapon, it lets out an animal pain moan, two different kinds of moaning, a low pitched scream or a distorted gurgle as it is being knocked and lie down, particularly dropping a bonus credit star. When killed by a flamethrower, its skin burnt. However, if it is killed by an explosive weapon, it silently lies down without making a death cry as a puddle of blood coming out from its body as a gib-like death animation.
- "(Playable character's name) was slain by a Humanoid Alien."
- As a genus of this creature, the term Xenorius is a Latin equivalent of Xenorians (later used in the direct sequel) and described as the aliens who came from the planet Xenoria.
- The Greek word "anthropoeidís" (ανθρωποειδής) means "humanoid" in English and is used as this creature's species although it is named in Latin.
- In this word, it is translated as a combination of o ánthropos (ο άνθρωπος) (human) and eída (είδα) (resembling).
- As an adjective, the word "anthropoid" is also derived from Greek defining the resemblance of a human being in terms of either shape or appearance. And another meaning is described as having ape characteristics.
- In the game, Humanoid Aliens made their zombie-like appearance due to their walking or running animation. However, as an alien, it features human intelligence.
- Upon the Humanoid Alien's appearance, it resembles any human zombies and the Imp from Doom.
- The Humanoid Alien's alerting sounds and death cries are came from Doom, usually for former humans/zombies and imps.