I'm running a campaign where the players have found themselves in the Shadowfell. I have no idea what sorts of monsters or people would be iconic for this realm. Is there a comprehensive list somewhere? We happen to be playing 5e, but I can make use of information from any edition.
Detailed information on the 5e version of the Shadowfell is still pending (hopefully in the Dungeon Master's Guide!) but here are some typical inhabitants from 4e:
- Shadar-Kai, near-humans with tattoos and scars that rejoice in battle and have shadowy abilities.
- Shadow creatures (none are in the Basic Rules bestiary, and the type may not exist at all in 5e).
- Ghosts of the dead on their way to their final destination.
- Corporeal undead, typically the result of ghosts who refused to pass on.
- Any horror-themed creature, as the Shadowfell is basically Spooky Halloween World.
Given the limited creatures available in the Basic Rules, I'd provide a lot of undead and reskin some other creatures: turn wolves into "balehounds" and ogres into "flesh terrors" and so on.
You can generally assume that each normal race has a Shadowfell subrace or equivalent with gray skin, shadow-themed abilities, and more piercings.