Worldbuilding

The Death Star. The fact that the Empire built an incredibly advanced, moon-sized weapon of mass destruction not as a tool of conquest but as a means to deal with internal threats tells you everything you need to know about them.

And it works in so many other ways - it strengthens the WWII motives (referencing Hitler's obsession with oversized superweapons) and is of course a major plot source to countless stories, from the harrowing tale of the guy who pulled the superlaser trigger to the plucky rebels who stole the plans. No wonder they keep returning to it lol

For me its less so about the world-building itself but the presentation. I like when a fiction setting feels otherworldly like it operates on its own internal logic that makes you feel like a stranger in a strange land. One of my favorite ttrpg settings is vaults of vaarn, an indie game very much inspired by Caves of Qud and while the lore is fairly sparse, what you do get paints a vivid but weird history of an far future post-human earth. I think its neat.

For the wandering inn, they never fully explain things as the story goes a long. Which is really nice as the reader gets to discover things as the character does.

Isaac Asimov. Really just in general, but the foundation series does a great job of it. I've read it through a few times, and each time I grow to appreciate it more.

Patrick Rothfuss and the king killer chronicals is another great example, but fuck him for dragging out book 3 for so long.

Brandon Sanderson is also another great world builder.

For me it's MorningLightMountain and the Primes in general in Peter F. Hamilton's Commonwealth trilogy. It was just a really cool and unique idea for an alien species, and Hamilton succeeded in making it feel truly alien, explaining its motivations, etc. It was just a really well-realized aspect of the world.