Ash (Alien)

Ash was a synthetic employee of Weyland-Yutani Corporation and the science officer aboard the commercial towing vehicle USCSS Nostromo. He was serving on the ship during its fateful voyage in 2122 when it encountered a Xenomorph on Acheron (LV-426), an incident that eventually led to the destruction of Nostromo and the loss of all but one of its human crew. Ash's synthetic nature was kept secret from the rest of the crew, who assumed he was merely another human assigned to the ship. In reality, he was a Synthetic Sleeper Agent who had been placed on board Nostromo specifically to ensure the Xenomorph was returned to Weyland-Yutani for study and use in their bio-weapons division. His body was destroyed by the surviving crew, but Ash secretly uploaded part of his AI into Nostromo's shuttle, Narcissus, and escaped with Ellen Ripley. Chris Hooper eventually wiped Ash's consciousness from the shuttle's computer banks, finally 'killing' him.