Gello

Gello (also Gyllo or Gillo) was according to Byzantine tradition a girl from Lesbos who died as a virgin and became a demon that attacks pregnant women, new mothers, and infants. She appears in ancient Greek literature (Sappho mentions her) and persists strongly into Byzantine Christian demonology, where exorcistic texts name her among the leading demons of child-killing. She is cognate with the Babylonian Lamashtu.

Depicted as a young woman, sometimes beautiful, sometimes with a corpse-like pallor. She could be invisible or appear as a shadow over a crib. Byzantine amulets show her as a woman riding a horse, being confronted by the three holy horsemen saints.

Caused miscarriages, stillbirths, and sudden infant death. Could make nursing mothers' milk dry up. Attacked women in labor and caused childbed fever. Spread illness through mere proximity to infants.