Heya folks, this will be the last one of the threads on the orders. I originally wanted to do them in a single post, but this project got way too big when I started doing all the research on them. The remaining ones are below! Unfortunately, there isn't a bunch of information on what these factions are doing in BfA, so this post is going to be short and full of disappointment.

Tirisgarde

The Tirisgarde are an ancient order, first established as the elite mage-guard of Dalaran. They initially hunted down Aegwynn when she refused the orders of the Council of Tirisfal. It's also mentioned that they once did battle in the absence of the Guardian and wielded powerful artifacts.

The Tirisgarde are very much tied to Dalaran- a city which now seems to be remaining neutral in the Blood War. Indeed, the Tirisgarde feature no less than three members of the Council of Six in their ranks, and Khadgar seems to be quite involved, as well. Dalaran doesn't seem to have played any part in the war thus far, and so neither have the Tirisgarde.

Notable People:

Kalec: Former Aspect of Magic and Member of the Council of Six. Kalec was both a class champion and a major presence in Legion. He and Jaina had a short discussion in Before the Storm about her feelings, and mentioned how she did not feel she belonged in the Kirin Tor after the decision to readmit the Horde. He has no in-game presence in BfA yet.

Ersara Verrinde: The current Seeker of Wisdom for the Magisters. She was a class champion in Legion, and seeks out power and information for Silvermoon's benefit. While she has no presence in BfA, Silvermoon is now at war with the Alliance, and so it may have recalled its magisters- including Ersara, but this is largely speculation.

Order of the Broken Temple

The Order of the Broken Temple is a new order, formed after the Legion's assault on the Peak of Serenity. The survivors formed the new order and based it off of the Wandering Isle. This new order has not been seen past Legion, and since the Wandering Isle is off-screen, we have no idea what's going on with it.

Notable people:

Ji Firepaw: Master of Huojin and Champion of the Broken Temple. Despite what happened in the Siege of Orgrimmar, Ji still seems to be a part of the Horde. in A Good War, he's seen teaching monk students in Orgrimmar. He is a part of the Honorbound's forces and can be seen in-game on the Banshee's Wail.

Aysa Cloudsinger: Master of Tushui, and Champion of the Broken Temple. She can be found in-game at the Stormwind Embassy, and also as a part of the 7th Legion forces in Boralus.

Seeing as we only have Ji and Aysa seen in-game, and they occupy the niche of both class champions and racial leaders in their respective factions, we can't really make any guesses as to the fate of the order. It may simply be that they are still on the turtle, and the two chose to serve their factions when the war came.

Illidari

The Illidari not just the demon hunters, but all of the former servants of Illidan: Naga, Broken, Shivarran, and demon hunters. With Illidan serving as Sargeras' jailer at the end of Legion, we have no idea what's happened to his former forces. There are no major Illidari NPCs that have a presence in BfA. It's possible that their faction of naga may become relevant when the Azshara patch begins.

Kind of noteworthy character:

Marius Felbane: A demon hunter of the Illidari who works with the warlock Tehd Shoemaker. He appears on Zuldazar, the two apparently still hunting demons leftover on Azeroth.

Council of the Black Harvest

The Council of the Black Harvest was founded recently, after the defeat of Deathwing. They are warlocks who study forbidden powers once wielded by the foes of Azeroth. Thus far, none of the members of the Black Harvest have appeared in BfA in any capacity yet.

Knights of the Ebon Blade

The Knights of the Ebon Blade are the death knights who broke away from the Scourge's control and worked to defeat Arthas. In Legion, they struck a dangerous bargain with the new Lich King and moved their floating fortress to the Broken Isles.

Despite not appearing anywhere in BfA, the death knights did help set up some of the events of the expansion. When they raised Thoras Trollbane into a death knight, the Ebon Blade also were backstabbed by Galen Trollbane, his undead son, and Galen was slain. This very likely is what opened up the opportunity for the Alliance to rebuild Stromgarde Keep and re-settle Arathi at some point after Before the Storm.

The Deathlord of the Ebon Blade also invaded the Ruby Sanctum in Legion and caused some level of devastation there while trying to obtain information on an undead red dragon to raise into their class mount. These acts caused Alexstrasza to dispatch the red dragon Zallestrasza to Drustvar, in an effort to seal his remains against being raised into a frost wyrm. This culminates in the Life Preserver event there, which is the only appearance of a death knight in BfA. Death Knight players also get some special dialogue, which is a bit further down on that linked page.

Well, there we have it- all of the class orders are done, though a large chunk have no presence in any form in BfA. Please let me know if there's anything I missed in any of the other posts as far as class hall presence or NPCs- I don't play every class in the game and so I've had to rely on information from the wiki and wowhead for some parts of this writeup. Thanks for reading!