Editors Terry Rawlings and Peter Weatherley cut the film so cleverly so that we never have a clear notion of what the alien actually looks like until the very last shots.

Peter Bradshaw

The Guardian

Just as Ripley is the female action hero against whom all others are judged, so the alien itself, brilliantly conceived by HR Giger and, equally brilliantly, concealed by Scott and kept in shadow for much of the film, is one of the most terrifying monsters in cinema history.