Has anyone ever wondered where undead come from in the TES universe? I mean you traveled to oblivion where daedra are summoned from, so how about we get to see the place necromancers get their fodder from? Not that I'm expecting the "river Nix" or anything but hey it would be cool
A fact from lore: undead and vampires in TES are the result of a curse on mortals created by Molag Bal (http://www.uesp.net/wiki/Oblivion:Opusculus_Lamae_Bal_ta_Mezzamortie). So if there ever was a "realm" from which undead hail, it would be Molag Bal's, i.e. a Daedric realm.