Looking at some things. I see that each prince has a summoning date, and Hercine was summoned late and was not known to exist for quite some time. So, could perhaps there be even more who don't care about the affairs of mortals?

Each Kalpa they get cycled if my memory serves me correctly. There could be any number of beings that once were Daedric Princes. If i didnt misinterpret the whole thing.

*Waits for those more familiar with the idea to answer*

It's entirely possible. Take Jyggalag, for instance.

Doesn't mean it's likely, as the existing Princes aren't even that well-developed as it is, but you never know.

If Mehrunes Dagon could plot over many Kalpa, then wouldn't that mean the Daedric Princes retain much of their former selves?

Or Dagon's unique. A Daedra, like any other, unlike any other.

Jyggalag was mentioned in a book in Daggerfall.

The princes are known to enjoy meddling in mortal affairs. They make themselves known. Considering that mortals even know about Magnus, who does not meddle in mortal affairs at all, it's highly unlikely that there are any gods that we don't know about.

Full-blown Principalities?

Nope.

But the Daedric equivalent of petty kings, I think, are a very real possibility.

Yes, there could be any number of princes at one time, given enought power any powerful indvidual could become a deadric prince, for such as when the champion of cyridal became Sheogorath(althought i did take guidance from the previous deadric prince and special magics from the realm of madness)

If there aren't extra princes, there's some kinda somethin out there.

Intriguing. Is that from the Dyus & Haskill interview?

Yes. Doubt we'll see any introduced within the next few games, though.

Yes I think it's possible. Who's to say that there aren't Princes that have no interest in mortals, thus have never been discovered by them?

Yep

Nineteen voids....oh my, so much delicious nothing to speculate upon and misinterpret.

Well, there are 16 Princes that we know of, so that leaves 3 Princes left unaccounted for...

...there are 3 parts to the Enantiomorph...

...so I would speculate that Auriel, Lorkhan, and Magnus are the other 3.

Auriel, Lorkhan and Magnus do not inhabit Voids. Magnus has his Radiance, which we refer to as Aetherius. Auriel and Lorkhan have Mundus.

Jyggalag and Sheogorath might have separate Voids, but that leaves two unaccounted for.

I was going under the very shaky reasoning that the Daedra just consider Mundus another void of Oblivion, much like how Mankar sees it.

Would the Soul Cairn count though? It's said to be an Oblivion Plane, right?

Soul Cairn! Of course! The Void without a Prince, the realm of soulless souls!

I must go and misinterpret this!

Doesn't really add up if you ask me. You have 16 princes, Mundus and the Soul Cairn if you wish that to be one. That gives 18. You could say Jyggie has his own realm away from Sheogorath but why then does he reform the Isles when he is back?

Whats stopping there being another thing similar to Soul Cairn? There are tons of little pockets in Oblivion anyways. Seems kind of meaningless to speculate on it with that in mind. Might be fun though.

There should be a huge difference between little pockets of Oblivion and the space that sits between the spokes of the wheel...

Edit: Unless that's the last part of course, an entire area of Oblivion reserved only for those little pockets of Oblivion

I'd argue the 19th void is probably something like the third person, or the third wheel. The specific number doesn't refer to anything in particular, just that it is in excess of those things that we bother counting. There are literally infinite third-person perspectives, but they're all called the "third person". You can have quite a few people acting as "third wheel", and you can even have the first third wheel actually be the fourth, fifth, or even sixth person in a group (if the couple in question swings that way). The 19th void is just "that void that isn't part of the 16 principalities, the Soul Cairn, and [the primeval void or Mundus]"

If not, the 19th void is the primeval void of Padhome/IS NOT.

That couple sounds rather rude, I have to say. Allowing five people in your bed but kicking away number six just sounds evil.

Number six is under Malacath's protection. Molag Bal fits in here somewhere too. That may be a little to graphic though.

"Outer Realms"

The myriad of churning Atronach hatching posts, Telvanni pocket dimensions, Imperial Battlespires, Sotha Sil experiments, rogue Magna Ge varliance and other stray creatia that coelesce into the hamlets of the void, existing for moments or millenia depending on numerous factors, swirling about with no certain masters only petty kings, arch-lich's, elemental daedra or forgotten spirits who inhabit them for a time.