The moroi is a type of vampire or ghost in Romanian folklore: a phantom of a dead person that leaves the grave to draw energy from the living. Its origins are given variously as an infant who died before baptism, the offspring of two strigoi, or a child born to a woman impregnated by a vampiric spirit. A female moroi is called a moroaică.
The name appears to derive from the Old Slavonic word mora ("nightmare"), with the masculine suffix "-oi" lending an augmentative and pejorative cast. Its boundary with the strigoi is far from fixed. The folklorist Tudor Pamfile recorded "moroi" in western Transylvania and elsewhere as one of the appellations gathered under strigoi, while another tradition holds the moroi to be the living offspring of two strigoi. The two read less as separate species than as overlapping, interchangeable categories.
The moroi is also frequently grouped with shapeshifting wolf-figures such as the vârcolac and the pricolici. This reflects how Romanian revenant and vampire lore is woven less from clean taxonomy than from a net of names that bleed into one another. That its nature never settles into a single point — where the ghost ends and the blood-drinking corpse begins — echoes the kind of horror that keeps sealed the question of what called it forth.