Warrant Officer Ripley is the iron-willed woman destined to battle the galaxy's ultimate creature. She makes logical decisions and tries to prevent Kane's return to the Nostromo while he is still under the control of the facehugger for fear that he could infect the rest of the crew. She also consults the ship's main computer to search for a way to kill the alien and, in her determination to survive, does not accept Ash's conclusion there is no escape.

As Captain of the Nostromo, it is Dallas who is told by 'Mother', the central computer, to reroute to the barren planet and investigate the distress signal. He takes Kane and Lambert with him to investigate the derelict spacecraft, and is the first to volunteer to hunt the alien in the Nostromo.

Lambert is one of the three explorers to investigate the alien craft. When the alien is loose on the Nostromo and killing it seems impossible, it is Lambert who recommends blowing up the ship and making their escape in the shuttle.

Brett and Parker are responsible for making repairs to the Nostromo. Once the alien is loose on the Nostromo, Brett is also responsible for creating the weapons the crew uses when they try to track and kill it.

Kane is one of the crewmembers to investigate the alien craft. While reporting to Kane and Dallas on what he sees in the nest of eggs, he is attacked by the facehugger which is then brought back to the Nostromo in the crew's attempt to save his life.

Ash is the only one who knows the company's motives in sending the crew of the Nostromo to investigate the derelict spacecraft. He studies the alien for the Company's Bio-Weapons Division and is ordered to keep it alive for return to Earth, no matter what the cost to the other crew members.

As Engineer, Parker, along with Brett, is responsible for repairing the ship when it is damaged during the drop to Acheron. Both he and Brett are only interested in making as much money as they can and complain loudly when the ship comes out of hyperspace early, as they want to be paid extra. He is convinced by Ripley and Lambert that they should destroy the ship and take their chances in the shuttle.