The void and the fel are two distinct and opposing cosmic forces.
Demons are beings of the fel
A voidwalker is obviously a creature of the void, but is labeled as a demon by warlocks.
Is this a contradiction in the lore that needs to be remedied or simply a case of warlocks mislabeling their subjugated minion?
Should blizzard reclassify voidwalker NPCs throughout the game? There’s a lot of them in outland with the demon label.
That would make sense but chances of it being reclassified after this many years of being set as such are probally pretty low.
I wouldn’t think they would go that far back nto make a change like that but, you never know.
There are plenty of Voidwalkers in the Legion.
I would imagine that just as some Warlocks summon Demons to fight the Legion, the Legion summons Voidwalkers to fight the Void.
And then since those Voidwalkers were summoned by the Legion, they are fair game for Warlocks too lol
Originally you had to force the voidwalker into a contract in order to use them.
That was the vanilla questline for it, so you actually summoned them differently from the other demons.
I would say they’re not demons, rather aberrations. If not aberrations, then fiends. I’d like to think that’s what spriests classify them as…
… but then again, political magic schools would be an absolute HEADACHE to tackle in this very lore-unfriendly game.
If i recall correctly you don’t summon a voidwalker so much as you dominate one with the bindings you put on its arms, and so it would be more of a case of a void being being subjugated using fel magic to be used for his sturdy properties.
Hmm. There are Life Wild Gods from the Emerald Dream and Death Wild Gods from the Shadowlands but I don’t think we’ve given them too much distriction besides calling the Wilds Gods of the Shadowlands as Loa however both can be affected by binding the Emerald Dream. 
…perhaps creatures of the Void and Fel can be bound by the Nether thus making them demons?
warlocks also use some other magic schools too
The preconceived belief that voidwalkers are demons is unfounded. In reality, they are composed entirely from blueberries.
Kinda wished that Blue Berry was more connected to the shaman side of how certain warlocks came to be.
Fel Corrupted elementals shackled into the bonds of servitude. We see plenty of them in WoD and Legion. Fire Elementals burning with sickly glow of Fel Fire.
We have trinkets and combat companions that are available, but no glyph / barbershop skin to give poor ol’blue berry a nice baby vomit green texture.
" I… don’t… like… this… place."
Change the type of jam. But there is only one man who would dare to use raspberry.
Would kill for a Spaceball themed Voidwalker now lol.
There’s no reason a void creature cannot identify as a demon.
It is a contradiction. Void and fel were the same thing originally. “The void” and the “Twisting Nether” were the same thing. There are a lot of such lore bandages holding things together.
They aren’t void walkers.
They’re void floaters.
They don’t have legs.
This dates back to TBC. I’m pretty sure we saw voidwalkers in Outland. And when I was leveling a warlock in Classic Wrath I did a quest to pick one up in the Blood Elf starting area, again a TBC area.
Explains why I taste blueberries every time I try to make chili fries out of em
Not opposing. Just different. Void is the opposite of holy and fel is the opposite of arcane.
I think it’s more a case of certain lore not being as well defined back in the day. Specifically stuff to do with the void. Spooky creature that warlocks can summon? Well that’s a demon, brother! Shadow priests? Well they’re just creepy guys who are into death and such. We also didn’t have the “aberration” label in the early days. I think that would be a better fit for them today.
I think the misconception here is that warlocks are purely fel casters.
They arent.
They are DARK casters that tap into forbidden magic. They are just mages and shamans who tapped into forbidden stuff. The fel is a big part of it yes but they also have alot of shadow abilities as well.
The classification is just an error since voidwalker was an iconic pet in classic and they just never got rid of it when they really started classifiying void and fel seperately.
I like it this way anyways. My warlock is a troll and i headcannon him as more of a voodoo witch doctor as affliction.