Alien

A commercial towing vessel is diverted to answer a signal. The film's first act is an industrial workplace: people who have not been paid properly, a captain who is not respected, and a company that has already made a decision about them.

Giger's design is why it endures. The creature is biomechanical, sexually explicit in ways the studio did not fully register, and shot in fragments, wet and in shadow, so it is never fully legible.

The chestburster was staged with the cast largely unaware of the detail. Veronica Cartwright's reaction is real, and she was hit with blood she was not expecting.

Ridley Scott shot it on stages at Shepperton with a budget that ran out, which is why the last act is a series of corridors.

Ripley was written without gender specified. Casting Weaver, then unknown, is the single most consequential decision in the film.