Alongside the Angels, the Faceless were one of the earliest races created by Asha, the primordial Dragon of Order. Since they worshipped Malassa, the Dragon of Darkness, instead of Elrath, the Dragon of Light, the Faceless were directly opposed to the Angels. As a result, they fought each other during the Elder Wars, with a draw as outcome. However, by that time, the Humans were still worshipping Ylath, the Dragon of Air, and in order to win the War the Angels convinced them to convert to Elrath, as to have one common faith. This act opposed directly the Faceless to the Humans, who were up to that point coexisting peacefully, and tuned the Faceless into a secret society as they became banned from the Falcon Empire. Some of the Faceless, like Jorgen, for example, are missonaries to Malassa and constantly seek newcomers of faith to join their ranks, so that one day they could come out and triumph upon the Angels once again.
The Faceless are by definition keepers of many memories of past events ("Some memories should have been left forgotten. The faceless remember them all.") and often keep them near the books. In case of the Holy Empire, the source was kept in a secret library, alongside the Twilight Covenant (maintainer of balance between Light and Darnkess), until Kiril, possessed by the Demons, overtook it and brought it into Sheogh. Vainly trying to convince him to convert, the society was soon overrun by the Demons and almost felt apart.
However, before they vanquished from Ashan, Tuidhana, founder of the dark elves, made a pact with one of the Faceless; hence the dark elves carried on the will of Malassa and the knowledge transcended from the Faceless. It is presumable that shadow elementals are the remnants of the faceless since they are seen with the faceless in Inferno campaign and the final campaign of blood reputation.