Gello (), in Greek mythology, is a female demon or revenant who threatens the reproductive cycle by causing infertility, miscarriage, and infant mortality. By the Byzantine era, the () were considered a class of beings. Women believed to be under demonic possession by gelloudes might stand trial or be subjected to exorcism.
Gyllou, Gylou, Gillo, or Gelu are some of its alternate forms.
Etymology
Gello possibly derives from Gallû, an ancient Mesopotamian demon believed to bring sickness and death. The theory was advanced by Carl Frank (1881–1945) and supported by Martin Litchfield West, Walter Burkert, and others. The name is also preserved in the later word ghoul.
Greek folk etymology links the word to the root gel-, "grin, laugh," in the sense of mocking or grimacing, like the expression often found on the face of the Gorgon, to which Barb linked demons exercising a malign influence on reproduction. Such demons are often associated with or said to come from the sea, and demonologies identify Gyllou with Abyzou, whose name is related to abyssos, the abyss or "deep."
Classical Antiquity
According to ancient myth, Gello was a young woman who died a virgin, and returned as a ghost (, ) to do harm to the children of others. The myth is given as an explanation of a proverb by the second-century compiler Zenobius. It is noted that Sappho mentioned her, implying that Gello was a feared bane of children at least as far back as the sixth century BC.
The lexicographer Hesychius of Alexandria, who wrote in the fifth or sixth century but drew from earlier lexicons, glossed gello as a ghost () who attacked both virgins and newborn babies.
Since the Early Middle Ages, Gello has often been conflated with Lamia and Mormo, two similar mythological figures. Each originated as a single individual woman (with her own origin myth or aition) in Ancient Greece, but later developed into a type of frightening apparition or demon.
Byzantine Period
The gello eventually came to be regarded as a type of being, rather than an individual. The plural form gelloudes (), not found in Ancient Greek, came into existence in the Byzantine period, and used in the 7th–8th century by the patriarch John of Damascus, in his treatise (, "Regarding striges"). The gelloudes were considered synonymous to the () or "witches" by him, and described as beings that flew nocturnally, slipped unhindered into houses even when windows and doors were barred, and strangled infants.
The polymath Michael Psellos of the 11th century inherited the notion that the stryngai and gelloudes were "interchangeable". He described them as beings that "suck blood and devour all the vital fluids which are in the little infant". Psellus documents a widened scope of the Gello's victims in the beliefs of the 11th century. Gello were being held responsible for the deaths of pregnant women and their fetuses as well. Gello (or Gillo) was also blamed for the condition of newborn infants who wasted away, and such infants were called Gillobrota (), according to Psellus.
Psellus sought in vain for Ancient Greek sources of these beliefs, and formulated the theory that the gello derived from the Hebrew Lilith. Psellus further stated that the name "Gillo" could not be discovered in his usual sources for demonic names in antiquity, but were to be found in an esoteric or "occult" () Hebrew book ascribed to Solomon. Later, the 17th-century Greek Catholic scholar Leo Allatios would criticize Psellos's confounding of the gello and Lilith.
The 14th-century Greek ecclesiastical historian Nikephoros Kallistos Xanthopoulos still told of gelloudes that "bring the infant from the bedroom, as if about to devour him."
Middle Ages to modern age
Aspects of the superstitions about the gelloude may be followed from the Middle Ages from various writings and talismans, to a treatise written by Leo Allatius in the 17th century which reveal that medieval beliefs and practices were still to be found among the common people of his day.
Corporeal and phantom forms
Although reports of Gello's behavior are consistent, her nature is less determinate. In the 7-8th century, John of Damascus equated the gello with the stryggai that sometimes appeared in spirit form while at other times had solid bodies and wore clothing.