Demonic Invasion, often referred to by its TV Tropes nickname "Legions of Hell" or its non-TV Tropes alias "Armies of Hell", refers to a dangerous doomsday scenario in which demons or similar supernatural beings launch an attack upon the world - often enslaving or massacring humanity (as well as possessing them).
This style of invasion has been popularized in media such as the Doom videogames and films - unlike Demonic Possession, a Demonic Invasion is an open conflict and often endangers a sizable portion of humanity.
Demonic Invasion may also pave the way to Armageddon since it often breaks the balance of "good" and "evil" though many works that deal with Demonic Invasion portray devils as being capable of capturing worlds for an eternity if they desire - in essence transforming the world they have occupied into Hell.
The Shinto version of the afterlife is markedly different from most Christian versions (more akin to Purgatory); thus, in anime, not influenced by western notions of Hell and demons, Hell acts more as something of Lawful Neutral than evil regardless of how it looks, especially the classical Buddhist and Chinese versions. Demons will be more like administrators than tormentors, often taken to the extreme.
Fiction Dealing with Demonic Invasion
- Doom series.
- Devilman.
- Devil May Cry series.
- The Legend of Zelda series.
- Middle-earth series.
- Evil Dead series.
- Warcraft series.
- Warhammer 40,000
- Dragon Age series.
- Diablo series.
- Gravity Falls
- Sword Art Online Alicization arc.
- Supernatural series.