A demon is a supernatural being, typically associated with evil, prevalent historically in religion, occultism, literature, fiction, mythology, and folklore; as well as in media such as comics, video games, movies, anime, and television series.
In Ancient Near Eastern religions and in the Abrahamic religions, including ancient and medieval Christian demonology, a demon is considered a harmful spiritual entity which may cause demonic possession, calling for an exorcism. Large portions of the Jewish demonology, a key influence on Christianity and Islam, originated from a later form of Zoroastrianism, and were transferred to Judaism during the Persian era.
In Western occultism and Renaissance magic, which grew out of an amalgamation of Greco-Roman magic, Jewish Aggadah and Christian demonology, a demon is believed to be a spiritual entity that may be conjured and controlled. The supposed existence of demons remains an important concept in many modern religions and occultist traditions. Demons are still feared largely due to their alleged power to possess living creatures. In the contemporary Western occultist tradition (perhaps epitomized by the work of Aleister Crowley), a demon (such as Choronzon, which is Crowley's interpretation of the so-called 'Demon of the Abyss') is a useful metaphor for certain inner psychological processes (inner demons), though some may also regard it as an objectively real phenomenon.
The original Greek word "daimon" did not carry negative connotations. The Ancient Greek word δαίμων daimōn denotes a spirit or divine power. The Greek conception of a daimōn notably appears in the works of Plato, where it describes the divine inspiration of Socrates. In Christianity, morally ambivalent daimons and the Egyptian decans were replaced by demons, forces of evil only striving for corruption. Such demons are not the Greek intermediary spirits, but hostile entities, already known in Iranian beliefs.