Shadow satyrs are satyr-like creatures born of the Emerald Nightmare that serve under Xavius, the Nightmare Lord. The exact origins of the Shadow satyr are unknown but there is a subtle implication of them being the corrupted dream form of the unwaking or even satyrs who have somehow entered the Emerald Dream. However, it is also possible that there are in fact different types of Shadow satyr, much like their are different types of elves.
Regardless of their origins the shadow satyr are known to be incorporeal creatures that not only exist with inside the Nightmare but places on Azeroth that has come into contact with it as well. They may also have the ability to manifest into Azeroth from anything touched by the Nightmare as a group of them used the corrupted leaves of Teldrassil to enter the world. As Azeroth fell deeper into the Nightmare the Shadow Satyr were seen fighting side by side with normal satyrs as they fought off the Horde and Alliance, while their master clashed with Malfurion Stormrage. After the defeat of the Nightmare Lord, the Shadow satyr seem to have been destroyed.