In Mesopotamian mythology, the lammasu were legendary creatures which had the faces of men, the bodies of lions, and the wings of an eagle. They were said to guard temples and would attack all but the purest good or the purest evil. Compare with the Sphinx.

In Demon: The Fallen the lammasu are a house of fallen angels. They were given dominion over the seas, and were meant to inspire humanity through the longings of both races. Before the War in Heaven they loved the humans, but the lammasu were the first of the houses to succumb to Hell. In the timeframe of the game, the lammasu fulfill such desires as ruining families, destroying businesses, and toppling governments.

In John Allen's HAVEN, the third book of the REALM trilogy, the Lammasu are mentioned as the overseers of the Limbic Sea. Their heavenly thrones subverted, they now reside in between realms and reign over the regions of Limbo.