Hello. I understand servers are likely lagged and coming up, and may be experiencing a record amount of volume.
That said, upon logging into my account, none of my characters are displaying as existing.
Is there anything that can be done to resolve this issue?
It most likely is a loading issue. I’d let it sit for just a bit, or try relogging. When everyone tries to get through the gate at once, well…
On Area-52 here and it is like launch day all over again. I got into the game, which was a slow process and when I got into the game I was on my way to the world boss. Once I landed I got disconnected. Go back into the game to see that all my characters on all servers are missing. 
Now I have the black screen.
One small caveat; during the downtime, I did change my battlenet id. If that won’t impact the presence of characters on my account, great, will wait it out. Otherwise, if that is a factor, I’d like to see if anything could be done, and to make you all aware. Thank you.
Same. this happened at launch too - same deal as then. Get a list of servers come up, none of which are mine, and no characters showing. I will try logging back in, in a few and hopefully it will resolve although last time y’all had to get involved on server side and poke stuff (that’s the tech term, right? lol)
same here im on Zul JIn my get comes up i hit it and gets %80 and then says toon does not exists
That shouldn’t matter if it is recognizing your credentials, Mournehub.
As an update, I can now clarify that upon selecting change realms, some of the other characters on my account are not displaying, and it’s only Tichondrius characters not displaying, suggesting that this is a server volume issue (to me).
All my main accounts are in Illidan US server, but whenever i choose that realm, none of my characters are loading, i cannot create a new character nor refresh my character list.
But whenever I choose a different server, everything seems to be working fine, my characters are being displayed properly and i can log in to them just fine.
This only happens in illidan where majority of my characters are at and my main toon is located at.
Thank you Orlyia for your rapid responses and the clarifications, I appreciate you.
Even more awesome is seeing others online, and still 17 minutes, no que timer, or character to even select.
dont be so salty, bud. everyone is trying to log on and Illidan is a full sever. Take a lesson from the game and think about the virtues of patience!
All my toons on illidan i cant event select them/ see them. im able to log into my alts tho on mannoroth 
Imagine not being ready for a mass amount of people logging in. Illidan is hosed yet again.
Same here. Got disconnected while questing on Area 52. Now I’m completely unable to login. Got a queue now as well to get back into the realm.
Keep getting disconnected every 2-3 minutes and when this happens I either get put back into the queue or get a blank character screen.
Hoping this is fixed soon as I got a guild raid in just over 1 hour from now.
Hello Orlyia, Im getting a message when logging onto my main that my characters name is already taken and it kicks me out once fully loaded
Same here on Stormrage
This reminds me of way back when Internets was first becoming popular, and all that was available was dial up. The ISP’s over sold what they could actually handle. Blizz is doing the same thing, repeatedly.
From what I can see, it is just the ‘full’ servers that are giving me issues…
Not really a surprise there… 
That means your Character is in-game and hasn’t auto-logged yet, Badting. Usually takes 5-10 min for that to happen. Usually occurs if you have to force quit the game - or leave in a manner other than normally logging out.