Cyborg Ash in Alien

Ash was a synthetic employee of the 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 LV-426, an incident that eventually led to the destruction of the ship and the loss of all but one of its crew.
The character is the science officer of the Nostromo, who breaks quarantine by allowing Kane back on board after he has been infected by an alien life form.

Ash is not human at all, as he appears, but is in fact a Hyperdyne Systems 120-A/2 android.

“You still don’t understand what you’re dealing with, do you? … Perfect organism. Its structural perfection is matched only by its hostility.”