Misterious Mist

The presence of Misterious Mist is a sign that there is something magical or supernatural about a certain place at that time. The mist itself is neutral, the type of magical or supernatural event swinging it one way or the other. It comes in a couple of forms.

Most common, is appearing with some form of magical or supernatural event. This is frequently the opening of a portal or gateway between our world and another, with or without the appearance of a being of that world. In this case, the mist is most often merely a by-product of the magic used.

The mist can also come permanently attached to a location, regardless of the surrounding weather. Usually hiding a location that is magical itself and/or contains something magical. Valleys, islands, ancient forests, magical villages/cities and combined places of magic/worship are all particularly susceptible to this. This mist frequently has unnaturally straight edges.

Sometimes, rather than being influenced by magic, it is naturally occurring mist that is emphasised to add to the atmosphere of a scene. It is not connected to magic itself, but tells the viewer (and the occasional Genre Savvy character) that it is a suitable time and location for something supernatural to occur. This is most frequently found in locations such as graveyards. On rare occasions, this type of mist will apply even if there is no actual magic or supernatural events involved; in this case it will be as though magic were used (ie. The Cavalry appearing out of the mist at the crucial moment).

The Mist is often also referred to as fog, vapour or even cloud. The disappearance of any Misterious Mist can be just as important as its presence, particularly if it is fixed to a location. This shows that whatever made the location mysterious and magical has now been removed or revealed.

Compare Empathic Environment, and the more sinister version of Mist Ominous Fog; also Smoke Out. Contrast Fog of Doom where the fog itself is sentient, and Super Smoke. May be used to provide Fog of War.

Anime and Manga

 * Sailor Moon: The first magical "attack" available to Sailor Mercury lets her fill the area of a battle with a literal Fog of War effect that her allies can see through, but which blinds enemies.

Film

 * The Secret of Kells gives a nod to Irish mythology by having the forest fill with mist when the fairy Aisling makes her first appearance. The mist dissipates as she becomes more friendly towards Brendan.
 * The valley of the Fountain of Life from Pirates of the Carribean: On Stranger Tides is filled with mist.
 * There of course is also The Fog which heralded the arrival of pissed off ghosts.

Literature

 * The aptly named Mistborn series has the mists at night. Unlike most examples, this mist is a good thing, since they're actually . It's more than a rumor that they defend the righteous.
 * It does become Fog of Doom during Hero of Ages, when Ruin magnifies the mists until they block out the sun.
 * In Deltora Quest by Emily Rodda the clearing fills with mist at the end of ‘The Forests of Silence’ when the Topaz summons the spirit of Jasmine’s dead mother.
 * Also, the mist hiding the Valley of the Lost. At the end of the 7th book it vanishes, showing that
 * The top of the Mountain in Rowan of Rin where the dragon lives is perpetually hidden in cloud regardless of the general weather.
 * Darkfall from the Legendsong Saga by Isobelle Carmody is the home of the future-telling soulweavers, and is actually called the Misty Isle.
 * Ruidean in the Wheel of Time is an ancient city shrouded by fog in the middle of a desert. Aiel who wish to become clan chiefs or Wise Ones must enter the city to learn the confronting truth of their race’s past; not all survive. The mist is dispersed  just after Rand reveals the truth to almost the entire Aiel population. The mist vanishing symbolises the loss of secrecy.
 * Also, mist appears when the Heroes are summoned with the Horn of Valere.
 * Daughter of the Forest uses mist when Sorcha’s brothers are . The mist is naturally occurring, but the description links it to their ritual and later
 * In Tamora Pierce’s Lioness Rampant Alanna is riding though rising fog at night when the Goddess appears for a chat.
 * Black London has fog that shows up right before mystical/supernatural events are afoot.
 * In The Voyage of the Dawn Treader the Isle Where Dreams Come True is surrounded by a mist. Merges with Ominous Fog.
 * Susan Cooper's The Dark Is Rising Sequence novel The Grey King uses mist a lot - it's referred to as the breath of the titular Grey King, hides his supernatural wolves in it and the King can summon mists at will.
 * Michael Moorcock's Second Books of Corum novel The Bull And The Spear invoke the feth fiada during the attacks of the Fhoi Myore, a group of evil giants who've brought magical winter to the land. Freezing mist would always precede their coming and accompany their attacks.
 * In Harry Potter and the Goblet of Fire, one of the obstacles in the maze for the final Triwizard task is a golden mist. When you step into it, you halluncinate that you've turned upside-down and are standing on the sky. Harry is afraid that if he moves a foot he'll plummet head-first to the ground thousands on feet below.

Live-Action TV

 * In the BBC's production of The Hound of the Baskervilles, Holmes, Watson and Lestrade are waiting for the titular hound to be released when a fog rises, obscuring their vision of the area. The mist is natural (the story does take place in England), but since the creature they're waiting for has a long and mysterious past associated with it, the mist not only presents a practical problem, it also adds to the tension of the moment. This is also the first time the creature will be clearly seen (an earlier appearance engineered by the villain was very brief and intended to instill fear in the viewers), so the impending revelation adds to the emotional weight of the moment.
 * Doctor Who:
 * Mistfall is a time of fear and hiding for the Terradonians marooned on Alzarius in "Full Circle". It's when the dreaded Marshmen appear and roam the forests and all of the Terradonians retreat and seal themselves inside their crashed starliner.
 * In "The Curse of Fenric", mist on the sea presages attacks and the arising of the Haemovores: the Vikings whom the curse followed from the Holy Land were terrified of a Black Mist that followed their longship all the way to Northumbria.

Oral Tradition, Folklore, Myths and Legends

 * In Classical Mythology, the gods can create a mist to hide themselves and others, usually for the purpose of rescuing a wounded soldier. This is called 'nephilistic rescue'.
 * In The Iliad, Aeneas (who later escapes from Troy and founds Rome in The Aeneid) gets rescued in the form of a mist by Aphrodite and Apollo.
 * Paris gets rescued this way by Aphrodite when he is losing a duel with Menelaus.
 * Irish Mythology knows of the féth fíada, the fairy mist (also known as ceo druidechta, druid mist). Supposedly, the féth fíada was used by the Tuatha Dé Danann to conceal themselves from observers; they also could travel in this mist—even over the sea. In stories set in later times, druids and even Christian saints are reported to make themselves invisible with magic mist.

Tabletop Games

 * The Dungeons & Dragons spell "Guards and Wards" is intended to help fortify a base or fortress against invaders; one of the effects of the spell is to fill the entire area of effect with a fog that friendlies can see through but enemies can't.

Theatre

 * In Brigadoon, the titular Vanishing Village is surrounded by mist.

Toys

 * Bionicle: the Akaku Nuva is unable to pierce through the mist in the Swamp of Secrets of Karda Nui.

Video Games

 * In The Curse of Monkey Island, one island is wreathed in spooky mist. The Lost Welshman has been, well, lost in it for years, and you need to find him to get the way to the next island.
 * In Escape from Monkey Island, there is the Mists of Time Marsh, plunging into which gets you displaced in time as well as space.
 * There are several places in the Pokémon games that have this. You're completely lost in it if you don't bring a Pokemon that knows Defog with you. One place that particularly fits this trope is a tower in Platinum. It's a burial place for departed Pokemon, and the upper levels are shrouded in mist.
 * The island of Lemuria in Golden Sun is surrounded by eternal mists and whirlpools that prevent access.
 * Not really mist, but... At one point in Twilight Princess, you need to acquire a particular smell before heading into a blinding snowstorm. If you go in without knowing the smell, you are returned at the very edge, implying you lost your way.
 * The Faron Woods has an evil purple fog falling on it that damages you, forcing you to use items and magic to either dispel or go above it.
 * In Persona 4 the world inside the TV is filled with fog, and on foggy days, mysterious events happen.
 * All of the towns in the Silent Hill series are enveloped with thick fog. It's not certain if said fog does anything, but given that it's, well, Silent Hill...
 * The mist originates as a practical solution to a hardware problem in the first game; the original PlayStation didn't have the power to adequately render a whole town, so the developers filled it with mist to facilitate this. The effect proved so chilling that it was maintained even when more powerful systems became available.
 * Final Fantasy IV, the village of Mist is in the Misty Valley and is home to summoners that can call magical beasts. It's implied the presence of mist in the valley and the cave leading to the rest of the world are spawned by the Mist Dragon the summoners have called to guard them.
 * Final Fantasy IX, lower parts of the Mist Continent are covered in mist that spawns monsters and are known to increase aggression in other beings. It's discovered early in the game that the Black Mages are beings manufactured using mist, and later on.
 * There's the mist in Final Fantasy XII which while invisibly around everywhere pools and is visible in more magical areas. This mist is also magically charged, creating a type of Background Magic Field.

Western Animation

 * A possible variation in the short-lived animated series Father of the Pride: Sigfried and Roy, who are extremely talented showmen and are capable of using actual magic, use mist from a (sometimes) undetermined source to initiate a dynamic introduction. This mist is usually followed by casual conversations with the humans in the room at the time, and (occasionally) accompanied by a tiny magic trick just to show off or demonstrate the point they were trying to make. On a more straightforward example, one episode had two up-and-coming stage magicians propositioned to be the duo's rivals, and, quite possibly, replacements. One of their advertisements showed them dressed in scarlet-red robes, chanting a spell while standing around a giant spherical object. While this is happening, mist has begun to envelop the stage they are performing on.