Henadic Theologian
Legend
But it is true, though: the very example of Wemic which you brought up illustrates that: there is some extra lore in FR stuff for them, but they can be used anywhere. Same with any NPCs or locations.
That is true of almost any creature in D&D, they took Darksun/Spelljammer Thrikreen and stuck them in FR and gave them their own lore. Few creatures in any setting can only be used in that setting.