Alien: Earth

Not essential, and the reason is structural rather than a judgement on the show. No film depends on it. It is set two years before the Nostromo answers its distress call, it shares no characters with any of the films, and all of them were made before it existed. You can watch every film on this list and never notice the gap.

What it has that the films do not is room. Eight hours is enough to be about the corporations rather than the creature, and the premise commits to that: an Earth in 2120 carved up between a handful of companies, with synthetics, cyborgs and a newer third category all treated as property. Noah Hawley is interested in who owns a mind, and the creature shares the show with several other organisms rather than carrying it alone.

It is also the first time this world has been shown at home. Every film happens on a ship, a station or a colony, far from anyone who could intervene, and that isolation did a great deal of the work. Moving the story to a populated planet changes the stakes in a way the series has never tried before, and whether it is an improvement is the thing people disagree about.

Watch it if the Weyland-Yutani half of this universe interests you more than the monster does. Skip it without consequence if what you want is the films.