Is there a master list somewhere, or does anyone know of them all?
I was building up a headless corpse mound in WIndhelm.

all named NPCs, corpses in dungeons that never reset (most dwarven ruins). everything else can potentially dissapear once the cell resets.

I've had plenty of named corpses disappear after a couple days.

Yeah this is wrong.

@Op there is no master list. It's just too difficult to figure out. Too many variables, some perma corpses loose the status others have it but are tied to their dungeon and reset when it does no matter where they are and the variables list goes on. It's just difficult to figure out

I found that if you cast another spell and it is a npc like sebastian lort and it says "master necromancer resisted" then it isn't a perma corpse but then again I have not played in months

I gotcha, toss in the glitchiness (like the strange corpse of Eltrys in Markarth after he's killed and then Thralled) and it's pretty tough to gather all the potential candidates. Well, if anyone wants to know specifics and names I have a headless collection gathering at my Windhelm graveyard.
If you do Blood on The Ice in a certain incorrect order, Susanna's body remains at the grave permanently.

Thanks everyone else, for your guesses and shrugs.