Warrant officer Ellen Ripley battles an extraterrestrial lifeform, commonly referred to as "the Alien" or Xenomorph.
When the seven-person crew of the spaceship ship "Nostromo" awakens midway through their cryo-sleep and journey home, they stop to investigate a distress call from an alien vessel only to be attacked by a mysterious life form whose lifecycle has only just begun.
Ellen Ripley is rescued by a deep salvage team after being in hypersleep for 57 years. The moon that the Nostromo visited has been colonized, but contact is lost. This time, colonial marines have impressive firepower, but will that be enough?
In 2179 a fire starts aboard the Colonial Marine spaceship ''Sulaco (fictional spacecraft)''. The computer launches an escape pod containing Ellen Ripley, the young girl Newt, Hicks, and the damaged Android (robot) Bishop; all four are in Cryonics stasis (fiction). Scans of the crew's Cryonics show a Facehugger attached to one member. The pod crash-lands on Fiorina "Fury" 161, a foundry facility and penal colony inhabited by male inmates with XYY syndrome, a genetic mutation which, within the film universe, gives the afflicted individual a predisposition for antisocial behavior. The inmates recover the crashed pod and its passengers. The same facehugger is seen approaching inmate Thomas Murphy's Rottweiler, Spike.
In 2379, military scientists on the space vessel USM ''Auriga'' create a cloning of Ellen Ripley, designated Ripley 8, using DNA from blood samples taken before her death. The Alien queen's DNA has been mixed in with Ripley's, so the clone grows up with an embryo inside it. The scientists extract the embryo, raise it, and collect its eggs while keeping Ripley 8 alive for further study. As a result of the xenomorphs' DNA inside her, the clone has enhanced strength and reflexes, somewhat acidic blood, and a psychic link with the xenomorphs. Additionally, the xenomorph's genetic memory allows the clone to have some of Ripley's memories.
As a spacecraft departs a planet, a humanoid alien drinks an iridescent liquid, causing its body to dissolve. As its remains cascade into a waterfall, the alien's DNA falls apart and recombines.
Business magnate List of Alien characters#Peter Weyland speaks with his newly activated Android (robot), who chooses the name "David 8" after observing David (Michelangelo). Weyland states that one day they will search for mankind's creator together. David comments on his own unlimited lifespan as compared to Weyland's, which unsettles Weyland.
In 2004, a satellite detects a mysterious heat bloom beneath Bouvet Island, an island about one thousand miles off the coast of Antarctica. Wealthy industrialist Charles Bishop Weyland (Lance Henriksen) discovers through thermal imaging that there is a pyramid buried 2000 feet beneath the ice. He attempts to claim it for his multinational communications company, Weyland Industries, a subsidiary of the Weyland Corporation, and assembles a team of experts to investigate. The team includes archaeologists, linguistic experts, drillers, mercenaries, and a guide named Alexa "Lex" Woods (Sanaa Lathan).
Following the events of Alien vs. Predator (film), a Predator (fictional species) ship leaves Earth carrying Alien (creature in Alien franchise) facehuggers, and the dead body of Scar, the Predator that helped Lex defeat the Xenomorph Queen. A chestburster with traits of both species erupts from Scar's body. It quickly matures into an adult Alien (creature in Alien franchise) and starts killing the Predators on board (in the extended cut, this happens on a scout ship that has been detached from the mother ship). A Predator's weapon punctures the hull and the ship crashes in the forest outside of Gunnison, Colorado, killing all but one of the Predators, who's severely injured.