Films: Xtro 2: The Second Encounter (1990), Xtro 3: Watch the Skies (1995)

Alias: Interdimensional Monstrosity, Alien Prisoners

Type: Alien

Location: Haunted home/Civilized Area/Forest/Cave

Height/Weight: Ranges from twice that of an average human to that of an average human.

Affiliation: Neutral

Summary: Remember that "charming" little incident with the Xtro alien and its progeny? Well, relax, because these guys have nothing to do with him aside from being aliens.

History: These wildly separate accounts of hostile alien life started with human arrogance, and ended in bloodbaths. The first was a massive alien summoned by tampering with alternate dimensions, while the others crash-landed on Earth in a desperate bid to get some solar power for themselves, and made an isolated island their home after they killed the scientists who tortured them.

Notable Kills: The way the first alien is born is...messy, to say the least.

Final Fate: The first alien is blown to kingdom come by a rocket launcher (though it is implied that more aliens could come out of the dimension), and the next manage to leave Earth after some difficulty and assistance from some people.

Powers/Abilities: The prisoners can turn invisible, heal each other's wounds, and emit a sticky corrosive webbing.

Weakness: Heavy artillery for the first alien.

Scariness Factor: 4-The first alien is a hulking, brutal monster that could actually go toe-to-toe with a Xenomorph, even if we barely see it. The next aliens, while sympathetic in their plight, still display a terrifying array of powers, even if they look a little stiff in some shots. Those close-ups are killer.

Trivia: Apparently Xtro 4 is in the works, but we have yet to see any of that.

-Xtro's original film director, Harry Bromley Davenport, was known for wanting nothing to do with the second film due to it having no resemblance to his original creation.