Pazuzu is a first-millennium BCE Mesopotamian apotropaic demon, the son of Hanbi and the king of the evil wind demons, who brings fever on the wind and is also the great opponent of Lamashtu. Bronze heads and plaques of him were hung in houses and worn by pregnant women, and the Lamashtu plaque sets him at the door driving her back. The sources are amulets and incantations; he has no temple, no priesthood, no festival and no mythology of his own beyond his parentage and his function. The figure became famous through the film The Exorcist, which is modern fiction.
Modern Practice
Pazuzu is used as a ward, not as a patron: the head at the threshold, the thing that faces outward so that what is coming does not come in. There is no cult to reconstruct, and any modern devotion to him is an invention that should be labelled as one.