Ash.

About Ash

Ash is a fictional character in the film Alien (1979) portrayed by actor Ian Holm who, while known in the UK as a stage actor, was at the time unknown to American audiences. Ash serves as the secondary antagonist of the first film. The character is the science officer of the Nostromo, who breaks quarantine by allowing Kane, a member of the crew, back on board after he has been infected by an alien life form. It is later discovered that Ash is not human as he appears, but a Hyperdyne Systems 120-A/2 android, a sleeper agent who is acting upon secret orders to bring back the alien lifeform and considers the crew and cargo to be expendable.