Shadow Men

"The great elephants, the basilisks in silver cages and the striped black-and-white horses of the Jogos Nhai are harmless enough. But I can see how the elders wouldn't want their younger members to see the warrior maids of Hyrkoon, who wear iron rings in their nipples and rubies in their cheeks. Or listen to the Shadow Men, who cover their bodies with tattoos and hide their faces behind masks and whisper dark secrets for a price."

- Jorah Mormont

Shadow Men are men who are known to whisper dark secrets for a price. They wear masks and cover their bodies with tattoos.

In the books
In the A Song of Ice and Fire novels, the Shadow Men are native to the Shadow Lands. They wear red lacquered wooden masks. Some of them have been known to engage in piracy and reaving throughout history, hence the maroon emperors of Yi Ti kept their court in Jinqi to better guard their Golden Empire from reavers from the Shadow Lands.