The monsters and daimons (demons) of Mesopotamia belonged to a constellation of Zwischenwesen -interstitial beings with supernatural qualities or capacities -that occupied the space between humans and their gods. As the "Other," if not always the enemy, their alterity was not only inscribed in their bodies but also reflected in their social alienation and geographical isolation. Strikingly imagined, where depicted or described, as morphologically anomalous or miscegenated (Mischwesen), the monsters and daimons lacked the kinship affiliations of both citydwelling humans and their gods and properly dwelt at the wild and inhospitable margins of the known world. This study explores their definition, functioning, and classification in a cosmos in which the overarching conflict was between order and chaos rather than good and evil, in which divinely organized and guarded civilization was ever threatened by the pressing and savage forces gathered in the wilderness beyond the city walls.In the gulf between humans and their gods exists an "other" world, an extraordinary supernatural landscape populated by all manner of "in-between" beings or Zwischenwesen. While alike in their transgressing of those borders and boundaries that delineate civilized human and divine lives and behaviors (as well as in their supernatural origins, qualities, or abilities), Zwischenwesen may be divided into an array of sub-groups that fulfill a range of (sometimes overlapping) cultural and religious roles.¹ In ancient Mesopotamia, a number of native terms for distinct types of Zwischenwesen are apparent in the extant textual corpora, so that gidim / eṭemmu (Sumerian / the context of more familiar Renaissance demonology, see Febvre 1982, 446 -450: "Deus quidem homini non miscetur, sed per id medium, commercium omne atque colloquium inter Deos hominesque conficitur, et vigilantibus nobis atque dormientibus," translated in n. 55: "Indeed God does not mingle with man, but it is through this medium [angels, demons, heroes, etc.] that all intercourse and conversation between Gods and men is accomplished, when we are awake as well as when we are asleep."