Tales say they lived in Azjol-Nerub long before the Scourge came, dwelling too deep for the nerubians to hunt them. The strange faceless ones are ancient monsters long imprisoned beneath the ice and recently loosed again.Faceless ones have a long magical heritage. They draw upon their race's legacy of arcane spellcasting traditions to increase their power. Although faceless ones have a racially low intellect, they have a strong heritage of necromantic magic.A second passage into the Old Kingdom has been discovered by the Scourge, and Baelgun knows the faceless ones will overpower even the undead and then be free to escape into Northrend proper, and so he vows to stop them.
If i'm right here ,these are the servants of the old gods and specificly Yogg Saron.