

Literally the Dusties in Sigil. They’re basically just necromancers who are also lawyers and loan sharks. They have contracts for their zombies. You sell your body when you’re alive, they pay you, you eventually die and now you’re a janitor at the local tavern for all eternity. They might even use those dudes who talk in rebuses as a PowerPoint to make the sale.
Don’t know about 5E but 3.5 at least allowed a fresh corpse to be brought to a cleric and revived for a fee, if your own party had no means of True Resurrection. The DM could always be a dick and claim they don’t want to come back, I guess. But if they are truly important to the campaign, surely that would be counter productive.