One thing I always find to be fascinating about the Star Wars fandom/franchise is just how many sub-fandoms (and sub-sub-fandoms) it has, especially how there are different kinds and how they overlap.
For example, you can say you're a fan of Star Wars, but most of the time, everyone is part of a different niche. The big three niches are the Original Trilogy Fandom, the Prequel Trilogy Fandom, and the Sequel Trilogy Fandom. Those are specifically in relation to the movies, where you like the theatrical films and the way they tell a story in three parts.
This is similar to, yet slightly different from the ERA sub-fandoms. The Prequel/Clone Wars/Republic Era, the Original/Empire Era, and the Sequel/First Order Era. There's also the Pre-Films Era, but that's a little complicated and not something I can easily tackle right now. These eras are not confined to the films, and instead are about the periods of time in which they take place. They can (and usually do) include the shows and books and comics and games and all sorts of external content. Someone can hate one trilogy, but love the era.
For example, a lot of people may say that the like the Original Trilogy as a set of films and that the other two trilogies aren't as good, but those same people will say that they love the era in which the prequels take place. This includes me, as I mostly dislike the Prequel films, but love learning about the lore and history of the Republic Era. So these are two distinct types of sub-fandoms within the Star Wars fanbase that can overlap and contradict each other in an interesting way.
But that's not all. As with most franchises, there are also sub-fandoms (though some may even hesitate to call them sub-fandoms) for specific shows/mediums in said franchise. Each show has it's own unique fandom, almost similar to how the trilogies have their own fandoms, but a little different. I and many others are fans of The Clone Wars specifically while not being as interested in other SW content (unless it heavily relates to TCW, like "Ahsoka" and other spinoffs).
This can kind of apply to other mediums as well, where someone may only be interested in the comics, or the games (which have their own sub-fandoms).
One of the other most interesting types of sub-fandoms in the SW fanbase (that is somewhat unique to expanded universes like this) is what I call the Lore fandoms. These fandoms likely don't just exist in the SW fandom (as is the case with extended universe with a large emphasis on worldbuilding), but they are a very notable and unique aspect of the SW fandom since it's actually one of the bigger categories.
They are basically sub-fandoms centered around a specific aspect of the lore/worldbuilding within Star Wars as a franchise. For example, there is a sub-fandom specifically for the Clone Troopers and their lore, which I am a part of. I also have a friend who is mainly interested in Mandalorian lore, which is it's own sub-fandom. One of the biggest sub-fandoms in this category is the Jedi-lore sub-fandom, where people are interested specifically in the lore and history of the Jedi (and often the Sith as well, but mainly just the Jedi).
While Star Wars is very story driven and can often contradict itself lore-wise, the worldbuilding is a big aspect of the franchise outside the movies. I think we owe a lot of that to the Prequel Era, which gave us the most lore in terms of overall worldbuilding and made the SW universe feel a lot bigger and more fleshed out than before. The Clone Wars was a pretty big player here, but I'd also give a lot of credit to the comics, which really seemed to push for extending and fleshing out the lore and worldbuilding of SW as a whole. The Clone Wars just solidified things and made it more mainstream.
This type of sub-fandom is overall very interesting and I think what a lot of people love about Star Wars: despite it's flaws and occasional retcons, the lore and worldbuilding of Star Wars is fascinating, and while the movies may hook a lot of people in, the lore is what makes a lot of people stay.
A common type of sub-fandom across many fandoms is character-centric fandoms, where a specific character has a whole fanbase dedicated specifically to them. I won't get too into this, since there are a lot of characters in SW, but I'd say that a pretty notable one (at least from my perspective) is the micro-sub-fandom centered around Ahsoka Tano in particular, as she is an incredibly interesting character who captured a lot of people's attention.
One type of sub-fandom that is mostly unique to the Sequel films and one of it's biggest sub-fandoms is the Reylo fandom, which is a ship-centric fandom. The other eras/trilogies don't seem to have sub-fandoms centered around specific ships (though they do probably exist), which is pretty unusual considering how many other fandoms have ship-centric sub-fandoms. Then again, I have noticed that most extended universes don't really focus on shipping quite as hard as others.
A similar, most difficult to explain fandom is one I call the "group fandom", where the (often micro) sub-fandom is focused around a specific group of characters, usually a friendgroup of some kind. Due to there being so many subplots and whatnot in the SW universe, there a multiple different groups of protagonists who may not have even met, but are all protagonists in different ways. An interesting non-SW example one may think of is the Marauders fandom in the HP universe, which is focused on a specific friendgroup.
In the SW universe, a few I can think of are the Obi-Wan/Ahsoka/Anakin trio (sometimes includes Rex as well), the 501st (slightly different from the Clone Lore fandom, though often an offshoot of it) and other Clone groups like the Bad Batch and Domino Squad, the Ghost Crew, the Corries, the OG trio (Luke/Leia/Hans), the Sequel trio, etc. These are usually confined to specific era fandoms, but they don't have to be.
So there aren't just different sub-fandoms within the SW fanbase, but also different types/categories of fandom:
Trilogies
Eras
Shows
Games
Comics
Lore Aspects
Characters
Ships(?)
Groups
And probably many more that I haven't even thought of yet. I just find it all so interesting how diverse the fanbase is in terms of groups within and what different people like about Star Wars.
Feel free to mention any other categories you think should be added to the list.