So for some reason I found Hroggar of Morthal dead... well I actually found his war axe floating in the air actually... not sure where his body went but I thralled the axe and went into the inn and he appeared next to me, naked... I didn't test him out or anything, just a civilian type so I didn't expect anything out of him.
After throwing his corpse into my Abandoned Shack I thought I might as well start the Laid to Rest quest and I thralled Laelette the Vampire, UESP lists her level as radiant 1-48, guess I got a weak version only took me a second to finish her off. Boy is she cute though, too bad she ain't strong enough for me to want her to have around.
*SPOILER* I did the Olava's token side quest, which was a reward from the DB. So I can find the Assassin of Old. It was at Hag's End and his corpse can only appear when you started the Olava's token quest. He's dead nord labeled as Dark Brotherhood Assassin and he has a full set of Ancient Shrouded Armor, since he was a corpse I believe he's permanent meaning I can make copies of this unique armor set over and over. Make some mad money! But I really don't need gold right now lol.
So I ended up doing the Forsworn Conspiracy quest today. Named NPC thralls:
Dryston - I actually didn't thrall him since I couldn't kill him without making trouble, but I'm pretty sure you can thrall him. He wears two pieces of leather armor and carries a dagger with him. He's breton as well and a warrior type.
Nana Ildene - She's a Breton and will use the spells fireball and a flesh spell then a one-handed weapon in the other hand. She only wears two pieces of unenchanted clothing and according to the UESP she has two perks Augmented Flames (rank 1) and Recovery (rank 1). I didn't test her out for too long and her corpse disappeared after a day or two. She had potential though.
Donnel - Basically a very weaker version of Nana, but his race is Elder. His spells from what I noticed was a flesh spell and flames, he will also use a one-handed weapon in his other hand.
Betrid Silver-Blood - Didn't actually get to thrall her since Nana used a raise zombie spell on her.
Nepos the Nose - Much like Nana but he has a flames spell instead and his race is elder. Basically a much stronger version of Donnel.
Uaile - a female Breton, I didn't get to test her out much. I know she is similar to Nana and Nepos, flesh spell, one-handed weapon, and probably some destruction spell. she didn't use a destruction spell when I fought her but I know she has one. I felt she had some decent potential like Nana and Nepos.
Tynan and Morven - just some weak Breton males, the both died really easily. No spells that I know of, just one-handed. I forgot which one but one got raised zombie by Uaile so I didn't get to thrall one of them.
I also thralled Grisvar the Unlucky from the No one Escapes Cidhna Mine quest. Just some weak guy in rags. I didn't get to thrall Thonar Silver-Blood either since one of those escaped forsworn fellows zombified him.
I thralled Eltrys as well, he's probably a perma since he's a corpse.
Basically all the bodies disappeared in a day or two, except for Dryston since I didn't get to kill him, I still have Grisvar though. Wish I could trade him in for Uaile or Nana, maybe even Nepos. Those three seemed like they would have some potential to be some decent thralls, not great but decent.
I also did the Revealing the Unseen mages' quest. Gavros Plinius resists Dead Thrall. Synod Researchers don't have any spells or their maqicka levels are probably too low for them to use their spells if they had any. They do use one-handed weapons with shield and a bow when from afar. I just tested them with falmer gear since that's what I had access to at the time.
Then I thralled Paratus Decimius after the quest was complete. He seems like the only worthy named NPC to thrall, that doesn't level with you, that only appears in the College questline. Other than The Caller of course. I believe he's a shock mage and the UESP lists that he has perks Augmented Shock (rank 2), Destruction Dual Casting, Magic Resist (rank 1), Recovery (rank 1), and Regeneration. So far he has used Lightning Bolt, flesh spell, and Lightning Cloak. When he was alive he had fast healing and summon flame atronach but I haven't tested him that long to see if he uses them while he's a thrall.