Are Bonewalkers and Bonelords exclusive to Morrowind/Vvardenfell? I was wondering if they are tied solely to Dunmer ancestral tombs, like Ancestral ghosts, as they don't turn up in Cyrodiil (don't know about Skyrim, haven't played it yet). If not, are they connected to necromantic summonings and animations of corpses? Are their constituent parts human, or are they made of other things.

I looked on UESPwiki, but it didn't say much, and I don't currently have my copy of Morrowind to hand to find out in the manual or any lore books in the game, so sorry if this seems lazy but I can't find much out from here.

They're both exclusive to Dunmeri "sacred" necromancy, I think. Dunno about the Bonelord, but the Bonewalker is a being raised/summoned to protect the Clan, probably through some sort of special ceremony. Some are also bound to protect Ancestral Tombs and the like because they did not serve the Clan well in life. I have no idea why they look so buff in comparison to the zombies in Cyrodiil and Skyrim, but I am guessing that's tied to their roles as guardians. Enhanced with magic, perhaps? Their ability to use Curses suggests that they have some manner of sentience and intelligence, unlike the majority of minions raised through profane/philosophical necromancy. I also seem to remember reading that most undead creatures created/raised through Dunmeri sacred necromancy tend to go mad after prolonged stays in the mortal realm.

Bonelords seem to be built out of multiple skeletons and imbued with some sort of spirit, probably ancestral. Could be that Bonewalkers are constructed in a similar manner as well. (They do have those spikes/rods or whatever poking out of them, so *something* is probably done with them as part of whatever ceremony is used to raise them.)

They're basically a zombie variant. Other races are familiar with the creation of bonewalkers (they're mentioned in Lord of Souls), but the Dunmer use them the most.

Hm, interesting. It's strange how they don't really pop up anywhere else. Maybe the 'recipe' for creating them is known only to Dunmer. I would have liked to have seen an Oblivion mod with them included - does one exist?

And if Bonelords aren't made of different skeletons, it'd be cool to see what they looked like with their flesh still intact.

I think the undead we saw in Morrowind were mostly Dunmeri creations. We didnt see any in Solstheim, but Mournhold sewers were full of them. Also, it would be logical to suggest that the Temple oversaw the creation of most undead guardians in Morrowind during it's time, considering most tombs had Tribunal altars and shrines.