Lilu (lilû) / Lilītu / Ardat-lilî

In Mesopotamian sources the lilu-class are conceived as spirits emerging from the unfulfilled dead — notably adolescents or adults who died before marriage or before conceiving children. Scholarship summarizes them as a category of spirits/demons causally linked to interrupted life-cycle rites; their social origin explains their role as agents acting upon the living, especially in sexual or illness-related ways.

Primary texts provide sparse physical description. In the Gilgamesh tradition a Sumerian term ki-sikil-lil-la-ke, understood in modern scholarship as equivalent to ardat-lilî, is described as dwelling in the trunk of the huluppu tree (rendered in translations as 'phantom maid', 'demon-maiden', or 'demon-girl'). Beyond such literary placements, direct bodily attributes are not supplied in the summarized sources.

Cuneiform and later scholarly summaries portray the lilu-class as nocturnal agents that afflict members of the opposite sex and are invoked in medical-magical explanations for illness. Modern scholarship (e.g., Scurlock & Andersen) situates references to lilû in treatments for neurological and mental disorders and, interpretively, in some contexts connected to sexually transmitted conditions; ancient texts treat them as causes of sickness, sexual danger, and other misfortune rather than cosmic or world-altering forces.