Faceless Ones were a faction of faceless ones in Warcraft III.
In World of Warcraft: Wrath of the Lich King, the term "Faceless Ones" generally applies to the bipedal, tentacled monstrosities seen in Northrend, most notably Ahn'kahet: The Old Kingdom, but also make appearances outside of the instance, such as in a cave in Icecrown where players can assist a captured Faceless One in making its escape. Several of the Faceless dwell below Icecrown Citadel itself, and can be witnessed if the brave dare to travel there.
The Faceless Ones serve the Old God Yogg-Saron, and this can be seen in the use of tactics relating to insanity and despair. Herald Volazj, is the final boss in the Old Kingdom instance, and even inflicts a period of insanity on players where they are forced to battle shadowy forms of their own companions. When a player is killed, the herald speaks in the language of the Faceless Ones, declaring "They drink your fear: it is the blood of life."
It is not known why some Faceless Ones, such as those in Ahn'Kahet, are referred to as Forgotten Ones, and the huge corpse located in Darkshore is also referred to by that term.