[[quoteright:320:[[Series/StarTrekVoyager http://static.tvtropes.org/pmwiki/pub/images/StarTrekBrig.jpeg]]]]
[[caption-width-right:320:Keep it down in there! We barely have enough budget to reuse old SpecialEffects!]]

->''"I just wanna get it on record that using force fields for doors in a space prison... is a bad idea. You know what would have been better? Regular doors, with locks! Locks that don't open when the POWER goes out!"''
-->-- '''[[AlternateUniverse Space Warden]] Cave Johnson''', ''VideoGame/Portal2''

A standard way to bar entry or exit for characters in SpeculativeFiction is to use a Force Field Door. It may be made of SomeKindOfForceField, glowing bars of PureEnergy, [[GeometricMagic concentric]] InstantRunes, or what have you. If touched, it may harmlessly shock or ''dematerialize'' the appendage doing the touching. Sometimes, especially if the field is invisible until touched, it leads to amusing situations where characters run face first into the field.

Aside from RuleOfCool, the advantage of such a setup is usually that it is immune to physical attack, or that it can contain StarfishAliens that could [[IntangibleMan phase]] or [[ShapeShifting shape-shift]] their way through ordinary doors.

Of course, the flaw in this immaterial marvel is it usually requires an outside energy source, or can be interfered with by using powerful ECM or MCM[[note]][[AntiMagic Magic Counter Measures]][[/note]]. So the hero can traipse past these obstacles by pulling the proverbial plug on it. Worse is when the outside energy source is on the ''outside'' of the Force Field Door, making disabling it as easy as beating up some guards and blowing it up[[note]](Which may actually be a challenge if guarded by EliteMooks or the like)[[/note]]. Or blowing a hole in the wall on the side, whichever is easiest. For some reason, the jailers rarely use physical doors outside the field (or wrapped in the field) as a backup in case of power failure.

If the force field door is on every side of a room, then it's like a ForceFieldCage, which redirects to this trope.

[[TropeCo/ForceFieldDoor This item]] is available for purchase thanks to TropeCo/TropeCo®.

There is a small amount of justification in this trope. Force field doors are very easy to use when you actually want to release someone at some point. Regular doors are just as vulnerable to blowing a hole in the side of the room. Having a system that fails open or fails closed is very much dependent on what you want the system to do.



[[folder:Comic Books]]
* In ''[[Comicbook/LegionOfSuperHeroes Legionnaires]]'' #22, the Planet Hell prison has force field doors on the cells. When the Legion and Workforce get locked up by the escaped prisoners, Karate Kid is able to find a weak point in the field, which shorts it out when struck.

[[folder:Films -- Animation]]
* ''WesternAnimation/MonstersVsAliens'': Gallaxhar puts Ginormica in a force field cage... which she then tears apart ''with her bare hands!'' Makes sense, as she is full of {{Unobtainium}}, which is more powerful than anything Gallaxhar has.
* ''WesternAnimation/TitanAE:'' Cale is thrown into one of these energy jails by the [[AliensAreBastards Drej]] (whose use of them is {{Justified}}: ''everything'' they build is made of force fields). It seems inescapable, until Cale realizes that the Drej phase through their own energy barriers all the time, and manages to work out how to do it himself.
* Likewise, the cell blocks in ''Anime/FinalFantasyTheSpiritsWithin''. So naturally, when the city's power grid goes down, so do the "bars" in the cells.

[[folder:Films -- Live-Action]]
* ''Nightlife'', a 1980s vampire TV movie starring Mirriam D'abo and Ben Cross, featured a doctor jury rigging a prison cell for a vampire by hanging ultraviolet lamps above the only doorway into a room, as well as on the ceiling a few feet down the hall in either direction. If the vampire crossed the beam, he burst into flames. See it [[http://www.youtube.com/watch?v=uzwD3uLGbwg#t=0m25s here]].
* ''Franchise/StarWars'' had several, most notably the barrier that forces Obi-Wan and Darth Maul to wait momentarily before their battle. Just about every large starship in ''Star Wars'' has some part of the hull, usually a hangar, that's open to the vacuum of space. How do crew members breath and not get sucked out into the void? Force fields. Seen in Episode III when Anakin blasts the force field generator over a Separatist battleship's hangar bay and air starts rushing out until a physical door closes over it.
* The cell doors in ''Film/{{Tron}}'' are beams of energy. Admittedly, they are already in the computer system and ''everything'' is energy, but there are still solid objects.
* In ''Film/StarTrekGenerations'', Soran protected his missile launch site with a massive force field wall. Fortunately, it didn't penetrate the ground, which allowed Picard to bypass it through a tight rock arch it happened to rest on. Also an inversion, as Soran is the one inside the force field.

* Creator/RobertAHeinlein's ''Literature/HaveSpaceSuitWillTravel''. When Kip and Peewee are on the planet Lanador they find a PeopleZoo with several persons held behind force field doors.

[[folder:Live-Action TV]]
* ''Series/StargateAtlantis'':
** Atlantis has one built into its Stargate, serving [[PortalSlam the same function]] as the Iris on Earth's Stargate, with the extra advantage that it can't be overheated by firing exotic weapons through the Stargate (something Earth's Iris has had to deal with).
** The city also has holding cells with energy shields covering actual bars. Surprising coming from the [[NeglectfulPrecursors Ancients]], who were usually very self-confident (case in point, a force field is the only thing holding the ''air inside Atlantis'' when it's in space).
* ''Series/StargateSG1'' once features an interesting variant -- a prison cell that uses the ''force of gravity'' as its "Force-Field Door". The cell is a long corridor with a dead end hooked up to an ArtificialGravity generator. When this is turned on, the end of the corridor becomes the floor of a deep pit, thus preventing escape for anyone inside (and ensuring a painful landing for an unprepared prisoner). When turned off, the "pit" becomes a corridor again, and guards can walk in or out. The resulting perspective shifts allowed for nice little CameraTricks. The flaw is the same as that of any Force-Field Door: [[NoGravityForYou cut the power]], and the prisoner can simply walk out.
* ''Franchise/StarTrek'':
** Cell doors in ''Series/StarTrekTheNextGeneration'' and ''[[Series/StarTrekDeepSpaceNine Deep Space Nine]]'' are energy fields.
** One ''Series/StarTrekTheNextGeneration'' episode "We'll Always Have Paris" had the bar variant in Dr. Manheim's lab.
** [[ShapeShifter Odo]] from ''[[Series/StarTrekDeepSpaceNine Deep Space Nine]]'' had to be held in a room surrounded entirely with force fields, to keep him from escaping in his liquid form.
** Add ''Series/StarTrekTheOriginalSeries'', e.g. "Assignment Earth".
** ''Series/StarTrekVoyager'' (in general a frequent offender with this trope) actually has an episode in which ''Voyager'' is temporarily converted into a PrisonShip, transporting a large number of dangerous alien prisoners in a converted cargo bay. Of course, all the cells added to the bay have Force-Field Doors. Predictably, a StandardStarshipScuffle ensues, and, lo and behold, the very first victim of SubsystemDamage is the cargo bay's power... The OhCrap expressions on the bridge crew's faces when they learn of this are priceless. "Oh, woe, if only there was some other way we could have locked up those prisoners!"
** ''Series/StarTrekEnterprise'', being set in the [[TheVerse 'verse's]] past, is the exception and has a good old-fashioned solid door for their brig, made out of some reinforced transparent material. It seems to work just as well as the force-field doors on all the later ''Enterprises''...
* In the ''Series/{{Firefly}}'' episode The Train Job, in the intro, Mal is thrown through what is evidently a force-field window: it vanishes as he passes through it, before reappearing a moment later. Assuming it performs the actual function of a window (keeping outside air out, and inside air in), it's most certainly an example of this trope, but they're never seen again.
* In ''Series/AgentsOfSHIELD'', Skye has to visit a BoxedCrook ([[spoiler:former agent Grant Ward]]) in a cell with one of these. It can go opaque or soundproof at the push of a button. Skye {{Lampshades}} one of the problems with this trope when she makes absolutely sure that there's no button she can push to accidentally turn it off.
* ''Series/Space1999''. The episode "The Metamorph" has a classic Force-Field Door for the prison cell on the planet Psychon. Normally invisible, it emits a brief flash that stun the prisoners when touched.
* ''Series/BlakesSeven''. In "City At The Edge Of The World", the VillainOfTheWeek forces [[MasterOfUnlocking Vila]] to break through a door to a vault that he's convinced has enormous wealth. Vila works out that the door is actually a disguised forcefield -- any force used against it only [[AttackReflector reflects back at the attacker]] (the villain gets his just deserts when he tries [[NoKillLikeOverkill blasting through with a laser cannon]]). Meanwhile Vila and the GirlOfTheWeek have gotten into the vault, only to finds it's a long-range teleporter to a distant spacecraft, where they'll live only as long as the oxygen that was transported with them lasts. When they don't die of asphyxiation, Vila has a EurekaMoment that the spacecraft has reached its destination, and the wall is another disguised forcefield door with the air seeping in from the outside world.

[[folder:Tabletop Games]]
* ''TabletopGame/DungeonsAndDragons'':
** Adventure S3 ''Expedition to the Barrier Peaks''. The spaceship's police headquarters had cells with 3 normal walls and one force field wall.
** ''D&D'' in general likes its magical force wall/cage effects. Depending on the edition, though, this can be justified in that those don't actually depend on an external power source and can be effectively indestructible if the exact right countermeasures aren't at hand, making permanent versions potentially actually superior to mundane physical barriers.

[[folder:Video Games]]
* These appear in ''VideoGame/BatmanArkhamAsylum''. They must be turned off before Bats can go further.
* These show up occasionally in the ''Franchise/CrashBandicoot'' series of games. Typically in the Warp Rooms, barring off access to later chambers until you clear the one before it.
* In ''VideoGame/HalfLife2'' some of the obstacles included energy fields to which you needed to shut off the power to get past. Often by literally pulling out a (inexplicably large) wall plug. These fields also allow combine troops (and trains) though while preventing Gordon and his rebel friends access.
* In ''Franchise/{{Metroid}}'' games, doors are, [[VideoGame/MetroidOtherM with one exception,]] surrounded by force fields. These are always ColorCodedForYourConvenience and thus a BrokenBridge till you collect the right upgrade. The ''Prime'' series actually justifies the door-shields: the door were set up to separate distinct areas from each other. The doors are actually motion-activated, opening when a sufficiently large life-form approaches it, but to prevent the doors opening and closing ceaselessly for the indigenous life, the force-field was set up, which could only be deactivated by an energy weapon from a sufficiently advanced species. It wasn't so much to keep people in and out of certain areas (though that's inevitably what they do...to Samus), but rather to ''[[MundaneUtility prevent wear and tear]]'' from constantly opening and closing.
* ''VideoGame/KnightsOfTheOldRepublic'':
** In ''Knights of the Old Republic 2'', the Exile, Atton, and Kreia find themselves in force cages repeatedly, which Atton [[LampshadeHanging lampshades]]. The fields cause "only mild electrical burns" when touched.
** Both games feature quite a few force field cages and doors. Some of these require you have certain members in your party before you can pass through them (e.g Jolee to get down to the Lower Shadowlands on Kashyyyk).
* In ''VideoGame/RaidouKuzunohaVsKingAbaddon'' [[spoiler:Dahn and his rogue Fukoshi]] are imprisoned in one. The "forcefield" can't be seen through, but the unoccupied cells in the same room have backup bars. (The forcefield is in place to block [[spoiler:their insect summoning whistles]].)
* In ''[[VideoGame/DarkForcesSaga Jedi Knight: Jedi Academy]]'', one mission involves escaping from a prison where an enemy has thrown Jayden. Each prison cell has four walls but no doors. The ceiling is a force field. Smart design, considering most people can't jump that high. Not smart when you put a Jedi (who can jump that high) in one of these cells and then ''[[WhatAnIdiot let him out]]'' to play [[HuntingTheMostDangerousGame the most dangerous game]] [[SuicidalOverconfidence with him]].
* Common in the ''Franchise/RatchetAndClank'' series. Sometimes Ratchet (or Clank) has to step on a button to open them, sometimes he has to trick or persuade some other character to step on the button, and sometimes he has to destroy the mechanism.
* The ''VideoGame/{{Fallout}}'' series has [[http://fallout.wikia.com/wiki/Repulsion_device multiple]] kinds of forcefields.
* Shows up a lot in the modern ''Franchise/SonicTheHedgehog'' games. They usually require you to flip a switch or destroy an encounter's worth of enemies to drop them. Other puzzles revolve around activating these to use as a walkway and sometimes even navigating mazes made entirely of them.
* In ''VideoGame/SuperheroLeagueOfHoboken'', Dr Entropy protects his first dastardly device behind a force field... but while the generator is placed on the inside, its power cord is plugged into an outlet on the outside, allowing the heroes to disable the field with one swift pull.
* In the Perpetual Testing Initiative for ''VideoGame/Portal2'', an alternate Cave Johnson learns the hard way why these things are bad idea on a PrisonShip -- especially when you consider power outages.
-->'''Cave:''' Man, those blue force fields looked good, though. Every time I saw one, I thought, "Wow! I am in space." Still, though... A door made out of paper would have been better in the long run. Would have at least slowed 'em down for a second.
* ''VideoGame/UnrealI'' has them all over, as well the consequences of turning off the power...
* ''VideoGame/{{Warframe}}'' features these heavily on both [[MegaCorp Corpus]] and [[TheEmpire Grineer]] ships. The former will deplete your shields, and fling you away from the door, as if you were struck by a shockwave, and need to be disabled by shooting (or staying out of sight of) security cameras, and the latter will proc Magnetic damage on you, draining all of your shields ''and'' energy, and are disabled by shooting ID scanner over the doorframe.
* ''VideoGame/{{Dishonored}}'' has force fields (called Walls of Light) that zap to ash anyone/thing unauthorized that tries to go through them. There are plenty of ways to circumvent them, however; there's usually an alternate entrance, you can remove the power source, you can rewire them to let ''you'' through and obliterate guards, and you can just throw stuff through the field until it runs out of power. One particular odd form of the latter is summoning a swarm of rats and guiding them into the wall. Two expensive ways to get through them involve DemonicPossession of a guard who ''is'' authorized and hop across that way, and the other is to use the advanced version of Bend Time to literally stop time and cross without fear of being zapped.
* In ''VideoGame/{{Arcanum}}'', [[spoiler:Arronax]] was captured by BigBad and kept in a magical force field capsule barely lagrer than his body for [[AndIMustScream two thousand years]].
* A standard in ''VideoGame/WarcraftIII'', turning these off is often a matter of killing the generator of boss powering them.
* ''VideoGame/PlanetSide 2'' uses forcefields in lieu of doors. Every base has impenetrable shields around the spawn building; at large facilities, these can be taken out by blowing up the generator that powers the spawn tubes. Other uses of shields are to protect vehicle garages -- which often have the generator on the outside - or to delay attackers from capturing the base's control point. ''Planetside 1'' used far more reasonable physical doors for pretty much every situation, only using force fields doors for the vehicle gateways in facility walls.
* ''VideoGame/TheCastlesOfDoctorCreep'' has the Force Field as one of the many obstacles you face. It is impossble to move through a force field (your character will stop just short of touching it), but on the flip side it will block a shot from the Ray Gun. By default, all force fields are on; the only way to shut a force field off is to press a corresponding button. However, the button will only shut the force field off for eight seconds; once time is up, the force field(s) that the button shut off will reactivate.
* ''VideoGame/XCOMEnemyUnknown'' has the aliens use force-fields for their doors and protection for their Elerium engines which the Humans incorporate into their own design.
* ''VideoGame/DarkSouls'' features magic barriers that bar the Chosen Undead from entering the Duke's Archives, the lower section of the Tomb of the Giants and the section of the Demon Ruins just before Lost Izalith until they acquire the Lordvessel and place it at Firelink Altar. Similar barriers will also serve to isolate a character within a certain area if they're being invaded or have entered another player's world.
* ''VideoGame/TheTalosPrinciple'': Most puzzles feature at least one of these. They appear as blue barriers and can be deactivated pointing a jammer at them, putting some weight on a nearby pressure switch, or pointing a laser of the appropriate color into a nearby receiver.

[[folder:Web Comics]]
* ''Webcomic/QuentynQuinnSpaceRanger'' (an InSpace spinoff from ''Webcomic/TalesOfTheQuestor''):
** During an arc skewering ''Franchise/StarTrek'', the main character is placed in a cell guarded by a force field and discovers he's been furnished with a replicator that can produce any food or drink he wishes. (Something the ''actual'' Trek examples didn't have, by the by.) He fabricates a glass of water and [[NoWaterProofingInTheFuture shorts out]] the door. [[http://www.rhjunior.com/quentyn-quinn-space-ranger-0030/ You can see it here]].
** Earlier, they entered the shuttle bay through a force field, much to Omnibus's [[http://www.rhjunior.com/quentyn-quinn-space-ranger-0015/ exasperation]].
* In ''Webcomic/ElGoonishShive'', Raven considers it "[[http://www.egscomics.com/?date=2009-06-06 standard lockdown procedure]]" to put up force fields sealing off all the doors and some of the hallways when his school is under a magical threat. Not that it stops Abraham, however.

[[folder:Web Original]]
* The ''Website/CollegeHumor: Troopers'' episode [[http://www.collegehumor.com/video/6439036/troopers-forcefield "Forcefield"]] has two bungling prison guards trying to convince their Princess-Leia-{{Expy}} prisoner that yes, her cell entrance is still blocked by an invisible forcefield.

[[folder:Western Animation]]
* The supervillain prisons in ''WesternAnimation/TheAvengersEarthsMightiestHeroes'' use this kind of door.
* In the ''WesternAnimation/DuckTales1987'' episode "[[Recap/DuckTalesS1E2Armstrong Armstrong]]", Armstrong sticks Scrooge and Gyro in a closet, behind a force field.
* ''WesternAnimation/{{Kaeloo}}'': In Episode 105, the door leading to the [[MakesSenseInContext magical staircase]] is a force field door. OnlyThePureOfHeart may pass through it; anyone who isn't pure gets an electric shock.
* The cells on Peridot's ships in ''WesternAnimation/StevenUniverse'' are of this kind, and they temporarily vaporize Ruby's hand when she touches it. Only one thing they didn't account on -- the cells are only designed to hold the [[HardLight projected]] Gem bodies. [[HalfHumanHybrid Steven's]] organic form had no problem [[NoSell walking straight through]] and can block the field projector to let his friends out.

[[folder:Real Life]]
* [[http://en.wikipedia.org/wiki/Plasma_window Plasma window]]. No, really.
* Considering that atoms are mostly empty space, and only feel solid due to the strong negative charge present on their surface (such that it is) which repels other atoms in a similar manner to what happens when you try to touch the south poles of two magnets together, ordinary doors are technically examples of this trope. Subverted in that you're just as much force-field as they.