Spinlok: Well, what is it? Dr. Femus: Okay, let's see: ornithious, carnivorous... Spinlok: Carnivorous?! It eats meat?! Dr. Femus: Exactly, genius! Those people are in a lot of danger!
~ Dr. Femus and Spinlock discovering what is in the chamber with the guests.
The "Alien", also known as "ExtraTERRORestrial", is the main antagonist of the defunct Disneyland horror attraction ExtraTERRORestrial Alien Encounter. It is a vicious and man-eating alien monster from a distant planet that is accidentally sent to Earth through an alien teleporter, wrecking havoc when it arrives.
An alien corporation called X-S Tech visits Earth and sets up their technology in the Convention Center in Tomorrowland, as explained by the company's chairman, C. L. Clench. They want to show off their new, advanced teleportation technology to the humans. After a flawed demonstration by the robot S.I.R., guests are shown to a chamber with the large teleportation tube in the center. They are seated in harnesses, and the demonstration begins, with Clench and two X-S scientists Dr. Femus and Spinlok broadcasting live from their planet.
Initially, the plans were to teleport a single guest to the planet to join them. However, in a rush of inspiration, Clench decides to send himself to Earth to meet everyone personally. Clench is teleported, but his impatience to get to Earth causes the beam signal to pass through another alien planet, this one unexplored and enigmatic. As such, Clench is lost and a different creature is beamed into the teleportation tube: the alien.
The X-S technicians begin to panic as the creature breaks out of the teleportation tube and cuts out the power, causing all the lights to go out and the safety machines to stop working. As guests sit in the complete darkness, the alien attacks and viciously mutilates and mauls one of the technicians in the rafters, causing his blood and the alien's saliva (which is actually just water) to spray all over guests. After presumably devouring the technician, the alien makes its way into the seating, snarling and breathing hot breath on the guest's faces and necks. It crawls around menacingly, stalking and sneaking up on its soon-to-be victims.
However, before it can execute its final attack and strike the killing blow, two X-S technicians attack it and are able to drive it back into the teleportation tube. The power comes back on as the creature is trapped in the tube. As the lights come back on, guests are released and the technicians go back to work, cleaning up the deceased worker and searching for the still missing Clench.
The alien is seen on some of the monitors before it escapes. It is shown to be a massive, orange reptilian monster with thick scales lining its body. It has multiple small arms, each with long, sharp spikes at the ends. It has small legs on the bottom of its elongated body, with longer ones at the end. It has large horns and two giant insectoid wings protruding from its back, large pincers, yellow eyes, and a gaping maw with sharp teeth and fangs.
In modern reimaginings, its color has been changed to green.
Another theory about why the attraction was closed states that it was because in November 22, 2002, Jeffrey Jones (the actor who also portrayed C. L. Clench) was arrested for possession of child pornography, causing Disney to shut down the one attraction that he acted in. Yet another theory is that, when word got out that those who complained to Customer Service about the attraction being too scary would have their tickets refunded, many people began to unfairly exploit this policy (i.e. They would spend a day in the park, go to "Alien Encounter" last, then complain about its content and get a refund, thus essentially getting a full day at Disneyworld for free). The theory goes that, when the Disney executives caught on to this, they closed the attraction to keep from losing more money.
In early drafts and concepts, the ride was supposed to be based off of Ridley Scott's 1979 horror film Alien, with a Xenomorph as the hostile alien. However, this idea was panned by Disney executives and shut down quickly, being deemed too horrific of a concept for Disney.