Demon

The English word "demon" derives from the ancient Greek δαίμων (daimōn), which denoted a supernatural/divine being or guiding spirit. In antiquity such entities lacked evil connotations, being considered spiritual beings that influenced a person's character (Socrates, for example, described his demon as a spirit that inspired him to seek and speak the truth, his "inward oracle"). But with the advent of Christianity, the demon took on a decidedly negative connotation in the Western world, eventually becoming synonymous with Satan/Devil in certain contexts (The King James Version of the English Bible doesn't even use the word "demon", opting instead for "devil").

And so, in some respects, the demon came became equated to the adversary of Jesus, bringing misery, suffering, and death to humanity (speaking of Christianity, the Roman Catholic Church has been particularly active in investigating demonology and demonic possession, although many other Christian churches also acknowledge and debate the existence of demons). More broadly, demonology is a complex subject, with an almost infinite variety of demons appearing in religions, occult beliefs, literature, mythology, and folklore all around the world (for example, Algonquian legend tells of a demonic spirit called a wendigo which possesses people, turning them into cannibals).

At any rate, a comprehensive overview of demonology is beyond our present scope, given that this Tag simply attempts to assemble a broad range of films featuring any sort of demonic creature (Mephistophelian beings, demons from the Far East - e.g. yōkai -, creatures drawn from Greco-Roman mythology, etc.), which means we can avoid delving into intricate philological debates as to the origin and iconography of various "demons" and instead focus on what's required for a film to receive this Tag: namely, a demonic presence. (+)

What constitutes "demonic presence" for this Tag?

1. For purposes of this Tag, "demon" will simply designate a supernatural being with evil intentions or conduct (note: this Tag will not, however, include specific types of demonic entities which already have a separate Tag).
   

   Some illustrative examples:

   "The Outing" (aka "The Lamp", 1987) won't receive the "Demons" Tag, since the film's malevolent genie already receives the more specific "Djinn" Tag. Conversely, the ravenous "Creeper" from Victor Salva's trilogy doesn't fit another, more specific category, so it will receive the "Demons" Tag.

2. The "demonic presence" requirement can be satisfied by either an actual depiction of the entity or through a clear manifestation of its actions.
   

   Some illustrative examples:

   Although the "Kandarian Demon" of "The Evil Dead" (1981) tends to remain hidden, its brief flights in POV shots and its destructiveness make it an extremely vivid - and I would say almost tangible - presence, justifying the "Demons" Tag. Sticking with Sam Raimi's oeuvre, a similar argument applies for "Drag Me to Hell" (2009). Conversely, despite the abundance of incantations and occult rituals, "Race with the Devil" (1975) boils down to a description of crimes perpetrated by a Satanic cult. Since there's not the slightest trace of any infernal beings, we'll simply assign the "Cult" and "Witchcraft" Tags to that particular film.

 
Trivia: the ancient (black) magic practice which involves invoking (i.e., "summoning" or "conjuring") demons is known as "goety" (from the Latin "goetia"). Goety is in fact an obsolete/archaic synonym for witchcraft or necromancy.