Seeing as vampirism is but a disease, does this mean TES vampires are not undead like classical vampires, and thus mortal? In Skyrim, vampire PCs are flagged as undead, which I found strange and is why I tried to find an answer in the lore (and failed). Also, does the disease affect the mind in any way?

Thank you .

In Daggerfall when you became a vampire you actually died.
I believe you woke up in a crypt then, though I have never been a vampire in Daggerfall so Im not sure.
This I suppose would classify them as undead.

http://www.uesp.net/wiki/Lore:Opusculus_Lamae_Bal_ta_Mezzamortie gives some insight into how vampires came to be in Tamriel.

There is quite some contradicting lore in TES, but maybe in this case it is the disease that kills you but then you wake up as an undead vampire. That's why a simple cure disease potion can cure you the first three days but after that (when you have died) it gets more complex than just curing a disease.

The point of vampirism is to mock Arkay's cycle of life and death. Thus, vampires are technically still alive, but for all intents and purposes, they take on the characteristics of being dead. So they do count as undead, but if you remove the disease from the person, you still have a living person. And as far as I know, perfect resurrection is impossible (or at least has not yet happened.)

(Also, on the topic of vampires, I've been meaning to ask, I know the sun damage thing is a typical vampire characteristic in other media, but in TES, does this have some connection to Magnus? Does Molag Bal not like him? Or vice versa?)

And here comes the rest of the folks saying Vampirism is not a form of undead. I don't disagree, then again I don't entirely agree either. Many times in lore it says vampires are undead. How is it logical to cure death? Well, how is it logical to have a time warp(Daggerfall)? I can give various ingame quotes saying vampires are undead, or simply implying it. But I will just use dialogue from Bethesda's newest game.

1. Ingame, Vampires are written under "undead".

2."When you have the gem, and have filled it return to me so I can perform the ritual. I will bring life to your dead body, vampire."-Falion.

Vampires are undead, Mannimarco http://www.imperial-library.info/content/arkay-enemy and all other literature confirms it and so does the words of Falion, as mentioned before me.

The best kind of dead, when you're still alive and kickin despite your organs screaming "NO!" My only problem is that they don't glitter. At least there are some nice little differences; Molag Bal is one bad dude.

Skyrim seems to confirm it. If you haven't noticed, the perk necromage will apply its affects to the PC if (s)he's a vampire now, and the perk specifies undead.

Yes! Haha! Huzzah!

I foresee an angry Hellmouth coming to spew violent profanity whilst trying to claim otherwise

Molag Bal seems to do it with Boethiah's priest. He even does this without (yet) having claim to the guy's soul.

He does this to the coc in oblivion as well.

Well Meridia hates undead, and Magnus is her father. Magnus seems to hate everything though.

A little OT, but are Ash Vampires considered undead?

Weren't the Ash Vampires just Dagoth Ur's lieutenants? They were corprus fiends like him.

Though, in hindsight, all the corprus monsters are pretty much cancer-zombies (instead of viral). So technically they're all just husks, void of any original tissues. And all filled with juicymagic corpral goodness.

No, ashvampires are just the dregs related to Dagoth Ur and all that other stuff. They have nothing to do with the undead vampires we see in other ES games. They are their own thing entirely.