Role in the FilmEdit
Ash was created and programmed to bring the Alien aboard the Nostromo. His task was simple: get the alien, and bring it back to Earth at all costs, even at the expense of the crew. He carefully monitored the expedition into the derelict ship as Dallas, Kane, and Lamburt explored it. When Kane was unexpectedly infected, he was brought back to the Nostromo.
Against Ripley's orders, Ash permitted an infected Kane to enter the ship. After Kane fell victim to a chestburster, the crew tried to find the alien, but Ash was secretly protecting it.
After Ripley found the orders and realized Ash has brought the alien on board deliberately, Ash tried to kill her. He was stopped When Parker unexpectedly attacked him with a fire extinguisher, decapitating him and ultimately revealing him to be android.
After Ripley, Lamburt, and Parker managed to learn the details of Ash's orders, they shut him down, and Parker set fire to his body.