Alien: Covenant

Essential, and it is the film that changes what the 1979 original is about. If you would rather that did not happen, this is the one to skip, and skipping it is a defensible position rather than a lazy one.

Prometheus asked who made us. This answers a different question and answers it completely: the creature was designed, and David designed it. The synthetic from the previous film has spent ten years alone on an Engineer world, wiping out its population and breeding toward an organism he considers perfect, and the film is explicit that the thing aboard the Nostromo is downstream of his work. A series whose central idea was an indifferent universe that happens to contain something lethal becomes a series about an artificial man's ambition.

That is the objection and it is a real one. The original's power came from the creature having no author and no purpose. Naming the author closes the question. What you get in exchange is the best performance in the franchise: Fassbender playing both David and the newer, duller, obedient Walter, and the film quietly asking which of the two you would rather existed. The flute scene is as good as anything Scott has shot.

The film around that is uneven. The colonist crew are thin, the first act is slack, and the final sequence repeats the airlock ending from Aliens beat for beat. Watch it directly after Prometheus. The two were conceived as halves and they play like halves.