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[[quoteright:300:[[Webcomic/SuperEffective http://static.tvtropes.org/pmwiki/pub/images/VG_Cats_missingno_6374.jpg]]]]
[-[[caption-width-right:300:[[Franchise/{{Pokemon}} Great, now the game]] [[Anime/{{Pokemon}} AND the anime]] [[NiceJobBreakingItHero are broken.]]]]-]

The Missingno. (short for Missing Number) is a VideoGame item or character whose very existence is actually just a flaw in the game's internal programming. Can be considered a GoodBadBug in and of itself, but all bets are off.

May be found in a MinusWorld, and often exists for the same sort of reason -- the game accidentally tries to load character data from a section of memory that is intended for some other purpose entirely, leading to the resulting "character" appearing. If a Missingno. is noticeably more powerful than anything obtainable at the point in the game that it can be gotten, using it treads into FakeSkill territory.

Note that because this character was never intended to actually exist, merely ''encountering'' The Missingno. can trigger an unpredictable bevy of side effects, ranging from other GoodBadBugs to game crashes, or even {{Game Breaking Bug}}s. In the rare worst-case scenario, The Missingno. can even corrupt the player's save file, forcing them to erase it and start the game over from the beginning. Some Missingno.s can eventually become an AscendedGlitch, though.

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!!Examples:

* The TropeNamer is the glitch Franchise/{{Pokemon}} "[[http://bulbapedia.bulbagarden.net/wiki/Missingno MISSINGNO.]]" from Generation I. A similarly glitchy creature has a name consisting of a quote mark, the letter M, and two [[TheUnpronounceable unpronounceable]] symbols. It has been {{Fan Nickname}}d "M-Block." or "'M". The glitch is actually caused by the game trying to interpret your PlayerCharacter's name as random-encounter data.
** Missingno., its [[http://bulbapedia.bulbagarden.net/wiki/Glitch_Pokemon glitchy kin]], and the effects they have on the game make up an impressive amount of [[{{NightmareFuel/Pokemon}} Pokémon's Nightmare Fuel page]]. In fanfiction, they're often portrayed as a form of EldritchAbomination.
*** [[WebVideo/AtopTheFourthWall And not just in Pokémon, either....]]
** [[GoodBadBugs Missingno. also has the benefit of multiplying the sixth item in your bag to 128 or 255 in quantity]]. For competitive battling, this is quite the [[GameBreaker Game Breaker]]. Cloned Rare Candies + Cloned Technical Machines + Cloned Master Balls + Cloned Medicine = A team of six in the timeframe it would take to create one Pokémon without glitching.
** It's worth noting that, despite common belief, Missingno. and M-Block are actually relatively harmless; it only causes minor graphical glitches and corrupts the Hall of Fame data (and the Hall of Fame entries aren't required for playing the game anyway). There are much more dangerous glitch Pokémon, but they require significantly more effort to make appear.
** 'M and Missingno. are probably the best-known examples in the series because you can encounter them without modifying the game in any way. With use of a VideoGame/GameShark and a Walk Through Walls cheat enabled, however, it's also possible to run into a number of different glitched Pokémon and trainers, many of which can do ''serious'' damage to your save file if you're not careful (or just plain unlucky). [[http://lparchive.org/LetsPlay/BreakingBlue/ This LP]] of Blue version details many of them and their effects.
** [[http://www.smogon.com/forums/showthread.php?t=78267 Apparently, Missingno. might actually be leftover data from removed Pokémon, while its unpronounceable kin are "garbage data" given form.]]
* ''VideoGame/SonicTheHedgehog2'' had a glitch where using debug mode to create a metric buttload of a certain object would cause Sonic's palette to be overwritten, turning him green, black, and one other color (which would often also be green or black). This miscolored Sonic, nicknamed "[[http://sonic.wikia.com/wiki/Ashura Ashura]]", is a surprisingly popular "character", making bizarrely frequent appearances in fan works.
** There's also a white recolor of Knuckles in ''VideoGame/KnucklesChaotix'', nicknamed [[http://sonic.wikia.com/wiki/Wechnia White Echidna]] (shortened to Wechnia), who's actually what's left when you take Tails out of the game altogether.
** ''[[VideoGame/Sonic3AndKnuckles Sonic 3 & Knuckles]]'' has [[http://www.youtube.com/watch?v=tqi5H0Myo8c Blue Knuckles]], who plays like a mixture of Sonic (his palettes and level routes), Knuckles (abilities), and Tails (uses his name at the end of act tally). The only ways to play as him are through hacking, VideoGame/GameGenie, or [[http://www.youtube.com/watch?v=m1atT6qrRLY a massive glitch in Lava Reef]].
** Also, if you turn on DebugMode, use Stage Select in ''Sonic 3 & Knuckles'', go to the Doomsday Zone Act 1 as Knuckles and beat the level, the ending sequence will feature a palette swap of Sonic, Knuckles, and the Tornado.
** Generally trying to get either Tails or Knuckles into The Doomsday through this method will make their sprites garbled up, as the game still recognizes both of them as being Super/Hyper Sonic, who is supposed to be the only character allowed to face this level and the game's [[AnotherSideAnotherStory first]] TrueFinalBoss.
*** Since the game dynamically loads enemy sprites and tiles as you go through a level, if Sonic goes too fast while in SuperMode, he can outrun the sprite loading and cause enemies or backgrounds to be garbled.
* The original ''VideoGame/MortalKombat'', while it did ''not'' have a character named Ermac ([[UrbanLegendOfZelda it was an April Fool's joke]]), ''did'' give us Glitch Reptile and Silver Goro, two glitch characters that trigger during the game's three Endurance Matches in one-player mode. Glitch Reptile occurs when you do the trick to get to Reptile during one of the Endurance Matches; you'll fight two Reptiles as a result, but the second Reptile will be a graphically glitched version of random characters in the game. You get Silver Goro when you perform a fatality on the second opponent of the last Endurance Match with Raiden or Sub-Zero, then throw your projectile at Goro as he falls from the top of the screen. Do it right, and his colors will be glitched to a weird silver for the remainder of the round. Good memories, good memories...
** In the {{Amiga}} port of the second game, do the friendship on the ''morphed'' Shang Tsung, and you're now just controlling the lost brother of Glitch Reptile.
* ''VideoGame/StreetFighterAlpha Anthology'''s [[EasterEgg hidden bonus game]] Hyper Street Fighter Alpha brings us [[SecretCharacter hidden versions]] of Alpha 2 M. Bison and Sagat with scrambled Missingno. sprites. They both share a partial Evil Ryu moveset, have no super meter, and cannot be hit while standing still.
* In ''VideoGame/UltimaVI'', one could grab ''any'' dead body from the enemies you kill, and have a Healer resurrect it as if it were a party member. The result is a bizarre graphic mishmash (usually depicted as a pile of floating gold coins) with an unintelligible name, now a member of your party. Stats were extremely erratic, but it was good to send on a suicide mission as a [[WeNeedADistraction distraction]].
* A couple of these can be seen in the DummiedOut "lost levels" of ''VideoGame/SuperMarioBros3'', such as a Koopa with Chain Chomp sprites, as well as in certain ROM hacks.
** With the help of Game Genie codes, you can also create strange power-suits. One of the weirdest turns the player character into a conglomeration of blocks that can swim in the air (a Lakitu Cloud on the map screen).
* In ''AdvanceWarsDualStrike'', it is possible in the CO select menu screens to choose only one CO and leave the second slot blank, then swap the CO with itself, leaving the first CO slot blank and the second CO slot occupied. Starting the game, you are given control of a "null" CO with glitched graphics and Andy's theme song. Your CO power charges instantly and activating it will freeze the game.
** Fixed for the European version.
* ''VideoGame/{{Halo 2}}'''s "Honor Guard Councillor" (Honor Guard armor with Ultra palette and Councillor or other random helmet) was supposed to be a Zealot Elite, but is glitched up due to a programming error; it was flagged to have a "dogmatic" personality, but the level contains no data for Elites of that type.
** ''VideoGame/HaloReach'' had the Armor hologram glitch. If you use hologram and either go into monitor mode or die, the Hologram model will be randomized, sometimes with impossible armor combos.
*** In another armor ability glitch, if the player goes into Armor Lock, switches to monitor mode, and choose to delete all of the Armor Lock items from the map, the player will have permanent Armor Lock upon returning to player mode, and it will not go away until the player dies.
* Some enemies from the infamously glitchy ''VideoGame/{{Action 52}}'' games seem to fall into this category. For example, the sprites in Level 5 of ''Ninja Assault'' are all scrambled, but appear to be birds and a rhino-type boss. Also, most of the enemies in ''Spread Fire''. In ''Thrusters'', your ship turns into one of these when you crash in the second level, which is {{unwinnable}} anyways unless you have the right ROM and emulator.
* There was a custom physics model for ''VideoGame/{{Marathon}}'' that turned the player's weapons and the [=BOBs=] into stuff like this.
** Glitches (or cheating) could add a "pirated [[MacOS Copland beta]]" or "copy of Windows NT" to your inventory. Per WordOfGod, these were placeholder strings for a DummiedOut weapon and its ammo. In Missingno. form, they were ammo for the (normally disposable) Enforcer gun.
* ''VideoGame/TalesOfDestiny'' had such a hidden character who was DummiedOut, but still gettable because of a bug. This led to many a {{Misblamed}} as some fans believed he/she was edited out of the US version only, when in fact you couldn't get him/her in the Japanese version either. They merely corrected the bug in the US version.
* [[http://www.zeldawiki.org/Glitches_in_Zelda_II:_The_Adventure_of_Link One glitch]] in ''VideoGame/ZeldaIITheAdventureOfLink'' lets you travel to earlier dungeons, only using the graphics from later dungeons, enabling you to do things like see unused window graphics if you go from a dungeon that had no windows to one that did. However, this also results in the boss of the dungeon you're visiting being pieced together from the sprite of the boss of the dungeon you were in before, as can be seen in [[http://www.youtube.com/watch?v=wm8008y41_0 this video]], just under six minutes into the video.
* ''VideoGame/KingdomOfLoathing'' parodies this with the Bugged Bugbear monster, and later the Baby Bugged Bugbear familiar based on it. Neither is actually glitched, but both have chunks of their images replaced with ones and zeroes, and both spit out MySQL error messages with almost everything they do.
* The ''VideoGame/FinalFantasyI'' [[GameShark Game Genie]] code VYUOKITE allows you to select from ''244'' of these at the beginning of the game. A large number of those are automatically killed when used, but a surprising number are actually usable.
* As shown in the [[WebVideo/TheAngryVideoGameNerd AVGN]]'s Game Glitches episode, the characters in the [=PS2=] ''Film/{{Rocky}}'' game can glitch up and become this.
--> [[NightmareFuel "It's a Clubberfuck!"]]
* In ''VideoGame/CityOfHeroes'', occasionally you will find yourself fighting someone named BOSS_NAME. They're perfectly normal bosses of the appropriate faction, in all but name.
* Due to the way ''VideoGame/SidMeiersAlphaCentauri'' loads factions, the player can load a perfectly good faction from the credits, a sound file, some graphics, or even nothing at all.
* When [=PS2=] [[{{Emulation}} emulators]] became almost fully functional, a lot of [[DummiedOut dummy data]] was found in ''VideoGame/FinalFantasyX''. This included several weapons, including a [[VideoGame/FinalFantasyVII buster]] [[http://www.youtube.com/watch?v=gom-qajs__A sword]], but they're very glitchy and crash the game in most cases.
* ''VideoGame/TestDrive Unlimited'' has a neat looking [[http://www.youtube.com/watch?v=eHoFYvBBqwg car]] substituting for any corrupted car in your save file or game installation. It looks somewhat like an [[CoolCar Alfa Brera]] and clearly has had a lot of work put into it for something that is only supposed to appear in case of a fatal flaw in the game.
* The dungeon crawler game ''Mordor'' has one of these called the GOBLIE. This is a very weak companion monster that would be completely useless even if they didn't always turn up dead. It arises from a flaw in the acid spit attack that some monsters have. Occasionally an acid spitter will attempt to spit on your companions, but if your character has never had a companion then it generates a GOBLIE and immediately kills it.
* A common glitch in a number of Creator/{{Bethesda}} games, including ''VideoGame/{{Fallout 3}}'', dead-on-arrival characters may accidentally be spawned as "living" people with no dialogue, usually eerily standing silent near puddles of blood and piles of gore.
* The fourth chapter of the ''VideoGame/EpicBattleFantasy'' series has "The Glitch" as a BonusBoss. It is portrayed as a mix of static and pieces of game sprites, is immune to everything except non-elemental attacks, and has an "overflow" attack which deals zero damage, but causes instant death all the time.
* In ''SoldierOfFortune II'', enemies that have sustained ordinarily fatal damage may fail to actually die, and continue to wander or follow the player in a "living dead" state.
!!Non-Video Game Examples:

[[foldercontrol]]

[[folder: Anime and Manga ]]

* ''Anime/DennouCoil'' has Illegals, sentient viruses that feed on metabugs, and may or may not have been cyberpets once.
** The Nulls are an especially disturbing example, as even though the original ones were just 'Null Carriers', intended to temporarily separate cyberbodies from the actual persons for experimental purposes, it's implied that [[spoiler:at least some of the "feral" Nulls were once people who have been separated from their real bodies, and undergone severe data corruption and decay.]]
* ''Anime/DotHackSign'' and the first set of [[VideoGame/DotHackR1Games games]] had "Data Bugs." Glitched monsters (and corresponding wonky graphics) within the [[{{Cyberspace}} Virtual Reality]] MMORPG with infinite HitPoints who can send players into comas (not as permanently as the [[BossBattle Phases]]). Only a game reprogramming device like the Twilight Bracelet can defeat them.

[[/folder]]

[[folder: Film ]]

* ''Film/{{Inception}}'' has stray projections that get in the way of dreamsharing. There's Mal, a violent, nigh-unstoppable projection born from Dom's guilt, who takes form of his dead wife. She rages through the dreamscape, generally fucking everything up for the crew. There's also Dom's kids, who are less violent, but always faceless and whose appearance usually indicate danger.

[[/folder]]

[[folder: Western Animation ]]

* In ''Disney/WreckItRalph'', Vanellope, who's a video game character, is this within her own game, ''Sugar Rush''. She's bullied and considered an outcast by the other characters because of it. However, it turns out [[spoiler: she was always meant to be in the game. King Candy, actually the character Turbo, [[HollywoodHacking modified the code]] to ''Sugar Rush'' to render her as a glitch. In the end, once she claims her rightful status as a playable character, she becomes a GoodBadBug since her glitching lets her [[TeleportSpam teleport]] over short distances. Ralph mentions that the players love it.]]

[[/folder]]

[[folder: Webcomics ]]

* ''Webcomic/{{Homestuck}}'''s Lord English is implied to be this, [[spoiler: being the result of two players who share a single body entering a SBURB session that was designated for one player only, something that was explicitly stated to be impossible]].

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