I recently noticed something that I am sure has been obvious to many people who play The Elder Scrolls Online for some time--that, although in-game, guilds are limited to 500 accounts, by using Discord you can effectively have guilds that are much larger.
How does this work? So for instance, you might have the Netch Lords, with almost 500 people and officers. The officers decide to make Netch Lords II. The officers are the same in both in-game groups (well, technically, guilds, but they are the same guild). The guild hall is the same (this is a long story as it differs from WoW, with no housing, and EQ2, with both houses and slightly distinct guild halls--in ESO a player buys a large house and shares access with everyone in their guild, thus, a guild hall). The members, however, are different (although sure besides the officers there could be regular members who are in both, as you can belong in up to five guilds). This means that, for instance, the in-game guild chats are distinct. Yes, officers make announcements to all the guild groups. And guild events can and do include everyone from each of the guild groups. But, the important thing is, that members of both groups (or however many guild-groups there are, I'm in one guild that is the fourth grouping, so like Netch Lords IV, and there are three previous guild-groups, each with about 500 members), are all members of the same Discord server. So all Netch Lord guild members (I, II, III, etc.), have a shared communication channel via Discord. Communication and community are inexorably intertwined (and as you can see they share the same root in English, from Latin).
I'm not really sure how to label such groups, although that isn't a big deal and they exist whether there are clear labels and distinctions. The world is beautifully complex, there are grey areas. What I mean is, if you just have the Netch Lords, you can say "this thing here is a guild." But if you also have Netch Lords II and III and there's a Discord, then the Netch Lords I is a guild but not in the way it would be without NLII and NLIII. You could say "there is a guild, called the Netch Lords, and it is comprised of three... things... guild groupings within ESO, and there is one Discord server for all of them, and that's in part why we consider these three in-game 'guilds' as one, larger guild." Possibly players have come up with good terminology for this kind of thing, perhaps in Reddit or in-game.
So, you end up with guilds that are quite a bit larger than 500 people, although they are not exactly the same as one singular guild in some ways. Some of my previous work looked at large guilds in ESO and only considered singular large guilds, I see I missed this aspect, although the findings for how guild leaders manage large guilds, from my experience so far in two large 500+ guilds, seem to hold.
(I made up the name Netch Lords, the Netch is a floating sky-jellyfish originally from the game Elder Scrolls III: Morrowind, and it is also in ESO. If there is a guild with such a name, my example here is not trying to be reflective of it.)