The Unknown Shadows (also called hidden folk) are magic entities which come from the world of Hsien. They are similar to the feral shadows that infest the Plain of Glittering Stone, but are more much more intelligent and can take animal shapes. In Hsien, the feral Plain shadows are referred to as the "Host of the Unforgiven Dead" to distinguish them from the Unknown Shadows.
Many of the Unknown Shadows started as Plain shadows which were altered by an ancient, forgotten proto-Shadowmaster called the First One or the Master of Time.
There are an enormous variety of Unknown Shadows, and many shared traits with common animals, including: panthers, dogs, owls and other birds, cattle, beavers, horses, crocodiles, and ducks. Unknown Shadows can be deadly, and many of them lurk underwater and pull their prey beneath the water to consume them. They can also be send to kill, as was demonstrated when one shaped like a giant duck with enormous teeth swamped Mogaba's boat to torture and kill his crew at Tobo's behest.
While the Black Company resides in Hsien, Tobo befriends the Unknown Shadows and becomes a messiah of sorts to them. The Unknown Shadows leave with Tobo when the Company goes back to Taglios and become the Company's key scouting resource under Tobo's direction.
Tobo gave names to many individual Unknown Shadows in his service, including:
- Little Boy
- Dragon's Eye
- Golden Eye
- Big Ears (male) and Cat Sith (female), siblings
- a group called the "Black Hounds"