In Jewish folklore, the possessing spirit that attaches itself to a living person is a dybbuk.
A dybbuk is traditionally understood as the unsettled or displaced soul of a dead person. The Hebrew-derived name comes from a word meaning “to cling” or “adhere,” describing the spirit’s attachment to a human host. It is generally portrayed as malicious, though stories vary about its motives and behavior.
The concept appears in Jewish writings from the 16th century and became especially influential in Eastern European Jewish culture. A dybbuk might remain in its host until its goal was fulfilled, its wrongdoing atoned for, or it was expelled through a religious exorcism. S. An-sky’s 1920 Yiddish play The Dybbuk later made the figure famous in modern literature and theater.
A common mix-up is confusing a dybbuk with a shed or mazzik. Those terms refer more broadly to harmful spirits or demons, whereas a dybbuk specifically denotes a possessing spirit, traditionally the soul of a deceased person.