We know that Ursoc was one of the last (named NPCs) to be judged by the Arbiter, and soon after that, every dead soul went directly to the Maw.
Therefore, let's keep all talk to a time line, no later than Emerald Nightmare raid.
Who went to the Maw? Not an answer like "the truly vile", but actual names? People we know from lore.
All the bosses/rares we fight in the Maw are new names, we have no connection to, lorewise, but there must be some we know?
Both Kael'thas, Kel'thuzad and Lady Vashj avoided going to the Maw; they would have been good candidates for the Maw in my eyes.