%% Image selected per Image Pickin' thread: http://tvtropes.org/pmwiki/posts.php?discussion=1319778916042180100
%% Please do not change or remove without starting a new thread.
[[quoteright:350:[[VideoGame/{{Growl}} http://static.tvtropes.org/pmwiki/pub/images/GSFfN_Growl_Montage_Clean_7875.JPG]]]]
[[caption-width-right:350:Poachers... poachers... more poachers...\\
%% When adding examples, remember that the boss must be irrelevant to the plot. If they are The Man Behind the Man or otherwise connected to the story, they
%% don't count, no matter how sudden their appearance is.
->''"I'm guessing if Megatron's not the final boss, it's gotta be Galvatron, or maybe Unicron, or Fuckitron, who knows... oh, it's [[Franchise/{{Godzilla}} Mechagodzilla]]. Of course, I should've known."''
-->-- ''WebVideo/TheAngryVideoGameNerd'', [[http://cinemassacre.com/2009/06/17/transformers/ review]] of ''VideoGame/TransformersConvoyNoNazo'' [[note]]It's actually someone who makes marginally more sense: [[http://tfwiki.net/wiki/Trypticon_%28G1%29 Trypticon]].[[/note]]

A Giant Space Flea from Nowhere is a boss with no relevance whatsoever to the actual plot, and who comes out of nowhere. They are frequently mindless creatures or beasts as opposed to actual characters, and tend to appear at the end of [[{{Filler}} unimportant plot threads]], such as {{Fetch Quest}}s.

Compare the non-video game boss equivalent, the BigLippedAlligatorMoment, which applies mostly to scripted scenes that came out of nowhere and have little or no mention of it afterward. If the boss and/or the battle is really weird and nonsensical even in the context of the game, there may be some overlap between the two tropes.

Note that, [[IThoughtItMeant contrary to what the name might at first seem to indicate]], the Space Flea is not always an EldritchAbomination, though overlap is possible. If it makes sense in the plot, it is not this regardless of how weird the boss might be. In other words, [[VideoGame/ChronoTrigger Lavos]], [[VideoGame/FinalFantasyVII Jenova]] and any other alien world-destroying parasites that are essential to the storyline of the game do not qualify, even if they're literal space fleas from the darkest depths of the universe. In more fantastical settings, they tend to be SingleSpecimenSpecies.

Also, note that most games that include RandomEncounters, or that have no thematic consistency to their enemies, are incapable of having a Giant Space Flea from Nowhere. In those games, even the normal enemies appear suddenly and [[ArtifactMook without any connection to the story]]; the bosses are therefore just a plain old instance of GameplayAndStorySegregation, same as the normal battles.

SubTrope of LoneWolfBoss. DiabolusExNihilo is the non-video game equivalent: a bad guy who pops up out of the blue, does some damage, and dies. Contrast OutsideContextProblem, which is a villain (or other problem) whose indeterminate origin is the source of their mystery and danger. Sometimes explained with AllThereInTheManual, but that might be an AuthorsSavingThrow. As you can see, many a BonusBoss is not included because they are technically a bonus boss and may even be outside of canon. Not ''necessarily'' related to GiantEnemyCrab, but it could be.

''Now available in the TropeCo/TropeCo [[TropeCo/GiantSpaceFleaFromNowhere catalog]].''



[[folder:Action Games]]
* ''Franchise/TheLegendOfZelda'':
** Dark Link from the Water Temple in ''VideoGame/TheLegendOfZeldaOcarinaOfTime''. In the middle of a water-themed dungeon with water-themed enemies, you suddenly get a room that holds a MindScrew and a fight against Link's darker side. There's a minority of fans that believe this miniboss would have made more sense in the Shadow Temple.
** Dark Link's original appearance as the FinalBoss of ''[[VideoGame/ZeldaIITheAdventureOfLink Zelda II: The Adventure of Link]]''. Link already defeated the guardian of the Great Palace (Thunderbird). For some reason, the Triforce Keeper draws out his shadow and they must fight. Many believe it was a final test to deem Link worthy of the [[MacGuffin Triforce of Courage]], and others believe it is the apparition of Ganon's shade, but no official explanation is given.
** Another clear example is Tentalus in ''[[VideoGame/TheLegendOfZeldaSkywardSword Skyward Sword]]''. Every prior dungeon boss had some story justification (Ghirahim was TheDragon, Moldarach was a fully grown version of the scorpion enemies the player had been fighting throughout the dungeon, Scaldera and Koloktos were objects in the dungeon enchanted by Ghirahim, The Imprisoned is the monster Demise turned into after his seal). Also in context are Bilocyte, the parasite that caused the disease that started tormenting Levias, and Demise, the FinalBoss and the master Ghirahim has wanted to revive); but this [[BuffySpeak giant tentacle-thing]] just inexplicably appears once you reach the boss room and tries to kill you and sink the Sandship for no reason. What makes this particularly egregious is that the MiniBoss of said dungeon had a pretty strong plot connection to the place, being the captain of the pirates who stole the ship in the first place.
** The ghosts/aliens/whatever that abduct the cows from Romani Ranch in ''VideoGame/TheLegendOfZeldaMajorasMask''. Who they are, what they are, and why they are there all go unexplained, and though they're somewhat important to a subplot involving the ranch itself, they have no bearing on the overall plot whatsoever.
* ''VideoGame/{{Okamiden}}'' has Asteroidean. While all the other bosses in the game have some sort of story relevance, Asteroidean is just a random starfish that is fought underwater, with no mention before it appears, no dialogue before or after the fight, and no mention of it for the rest of the game after. In fact, most people who play the game tend to forget it's even in the game to begin with.
* ''Franchise/SpiderMan'':
** In ''VideoGame/SpiderManVsTheKingpin'', Spider-Man fights a gorilla as a mini-boss while in Central Park looking for Sandman. Yes, a gorilla.
--->'''[[WebVideo/AtopTheFourthWall Linkara]]:''' Why is there a gorilla in Central Park?\\
'''[[WebVideo/TheSpoonyExperiment The Spoony One]]:''' And why does it hate Spider-Man so much!
** Most of the bosses in the console and PC tie-ins for the [[Film/SpiderMan1 film]] are either from the film or villains from Spidey canon. The one exception is the boss Spidey fights when he infiltrates [=OsCorp=], which is a HumongousMecha with a WaveMotionGun.
** In ''VideoGame/SpiderMan2'', Rhino qualifies. After you complete an assignment for Robbie at the Daily Bugle, Spider-Man hears an explosion and investigates it, and he sees Rhino as well as a bunch of thugs who tell him to "get the equipment back to base" before driving off. After Spider-Man defeats him, the equipment explodes and Spidey literally leaves him hanging. Nothing of him is heard again, nor is it shown what the "equipment" was.
** Weirdly enough, ''VideoGame/UltimateSpiderMan'' similarly has Rhino as the only boss who has no relevance to symbiotes (or the main plot, for that matter) at all. He's causing havoc in the city at the beginning of the game as the second boss, and after he's defeated and his mecha suit is broken, he never appears again.
*** Green Goblin could arguably count too, as his battle doesn't affect anything, but at least he's tied into the plot somehow (he's released by the Beetle who's collecting samples of super-powered beings, such as Venom, for Doctor Doom).
* ''VideoGame/TheMatrixPathOfNeo'' more or less proceeded with the plot of the three ''Matrix'' movies. Until the very end, when instead [[spoiler:all of the Smiths morphed into one giant "Mega-Smith" to fight Neo]]. Atari-esque avatars of the Wachowskis [[NoFourthWall stopped the plot]] at that point to explain how the metaphorical ending of the movies didn't translate well into a video game. This may be true, but it did feel like they were making fun of the player. ("Have fun... and enjoy enlightenment!" [Both laugh])
* Despair Embodied from ''VideoGame/DevilMayCry2''. He pops out of the carcass of the previous boss without any prior in-plot mention of his existence.
* ''Super VideoGame/AdventureIsland II'' does this ''twice''. The first one appears when you beat the giant bird hyped up as the final boss. Suddenly an evil wizard appears and steals Tina, and you have to play through the level ''again''. When you kill the wizard, a ''giant space octopus'' appears, which is the ''real'' final boss. And you fight him in ''outer space'' for some inexplicable reason. There's some eerie music and mist filling the room when you kill the wizard, indicating the abrupt change in mood, which is nice, but you'd think the player deserves an explanation for this nonsense.
* From the ''Franchise/RatchetAndClank'' series:
** The first boss of ''VideoGame/RatchetAndClank2002'' qualifies; it is never hinted at or mentioned before or after, and is pretty unexpected. While it seems to be the source of/related to similar, smaller enemies in the level, the character you meet after beating it doesn't mention it at all. The thing just kind of drops down from the ceiling.
** Similarly, there's the Mothership in ''VideoGame/RatchetAndClankGoingCommando''. Using Giant Clank to fight Thugs-4-Less' giant robots? Makes sense. Fighting a giant UFO that launches an army of respawning UFO-headed robots, both of which have no foreshadowing and never appear again? Not so much.
** There's the Warship (that's the only name it's given, and even then only if you leave and return) in ''VideoGame/RatchetAndClankUpYourArsenal''. It's a black gunship with a warp drive that shows up to make a platforming section on Planet Daxx difficult, and is then fought as an actual boss. It's not mentioned in the dialogue (it doesn't even get a post-battle cut-scene), there's nothing else with its design or abilities in the game, and its destruction does nothing but open the path to the goal.
** In Holostar Studios in the same game as the above, the player controls Clank through a platforming section to simulate the filming of another episode of ShowWithinAShow 'Secret Agent Clank'. So far so normal, but then you're suddenly thrown into the [[UnexpectedGameplayChange only Giant Clank section in the entire game]] to fight an actually somewhat tricky boss fight... not against the ShowWithinAShow's normal villain, but a four-armed dragon and his giant robot ninja flunkies. How does this make sense?! The only lead-up is the director making mention of 'The Terror of Talos' in the cutscene before the platforming, but it still comes out of nowhere, even in-universe (or... in the universe ''inside'' of the universe), since this is the only time we're shown that Agent Clank the character can turn giant in a spy drama series that a four-armed dragon has no business being in.
** In ''VideoGame/RatchetAndClankIntoTheNexus'', the titular duo is trying to get to an abandoned orphanage on planet Yerek where [[BrotherSisterTeam Vendra and Neftin]] are working on something. Eventually, they get there, and a robot named the Voltanoid [[HeWasRightThereAllAlong jumps out of a hole in a wall]] and attacks the heroes. He has no foreshadowing and comes out of nowhere, although later in the game, you have to HoldTheLine against a mob of Thugs-4-Less and another Voltanoid appears during the fight, and a [[PlayingWithFire fire-themed variant called the Blazebot]] appears in the [[MonsterArena Thugs-4-Less Destructapalooza]], suggesting that they built them.
* The Dark Eco Plant of ''VideoGame/JakAndDaxter''. It bears no resemblance to any other enemy and seems to have no alliance with them, while at the same time having no bearing on the plot. What's even stranger is that the entire Forbidden Jungle has holes strewn throughout with tentacles poking out that foreshadow the boss. While it appears that it'll be leading up to another great plot hatched by the Lurkers, it turns out to just be an angry flower.
* ''Immediately'' after defeating the [[SequentialBoss first]] final boss of ''VideoGame/{{Gungrave}}'', an "Alien Head" erupts from the ground, causing you to fall from the previous boss's arena to an entirely separate corridor, in which you fight him for the true final battle. There is no dialogue to give you any clue as to what the hell just happened, and after defeating it, you are inexplicably placed outside the structure you're in. Much like the rest of the [[TheVeryDefinitelyFinalDungeon final level]], the game [[AllThereInTheManual neglected to mention]] many key details about this being, including his non-mutated human form. Which is a shame, since he actually plays an important role in the backstory, but you wouldn't know this if you had merely played the game.
* ''[[VideoGame/{{Genji}} Genji: Days of the Blade]]'' is an action game which is [[InspiredBy based on Japanese history]]. [[http://www.pressthebuttons.com/2007/03/giant_enemy_cra.html The stages of the game will also be based on famous battles]] which took -- actually took place in ancient Japan. [[http://www.destructoid.com/behold-the-most-hater-ps3-video-possible-27094.phtml So here's]] this GiantEnemyCrab..."
* ''VideoGame/MetalSlug'':
** In ''2'', the entire game is fought against a human army. Then the last level has you fighting a bunch of Mars People with no build-up. Largely fixed in ''X'', which does a better job of foreshadowing them.
** Sol Dae Rokker, the boss of mission four in ''3'', is supposedly "an artifact of the solar deity that some Japanese believe in". Then again, some of the alternative routes of the game have you fighting acid-spewing snails, zombies, man-eating plants, titanic maggots, jellyfishes bigger than your submarine, and a squadron of the Japanese Army that isn't aware that UsefulNotes/WorldWarII ended decades ago, so it isn't ''too'' outlandish.
** The final boss of ''Metal Slug 5'' is another example of this. After fighting a terrorist cell for the whole game, your last opponent is... a giant demon. This was probably supposed to be built up first, as early on the game has what presumably counts as exposition in a Metal Slug game (one of the enemies from the first stage picks up a stone mask, gets struck by lightning, then starts showing up as some sort of cult leader in later stages) and several of the cut elements of the game (notably the Stone Tortoise and a cult leader on some sort of pedestal) point to this boss being the last of a ''few'' bosses. But in the final game, a demon just pops up out of nowhere.
* ''VideoGame/CaveStory'' is solid for most of it (even the fight against a tiny superfast mushroom makes sense). Monster X and Ironhead, on the other hand, are ''literally'' out of nowhere. All the latter gives you is "Something's coming", and the former just suddenly tries to run you over once the boss music suddenly starts (and its dying cutscene is [[BigLippedAlligatorMoment even more bizarre]]). Interestingly, Ironhead is [[TheCameo pulled directly out of]] [[VideoGame/SwimIkachan one of the creator's earlier games.]] There's also Omega, which unlocks the sun stones in the Sand Zone, and Heavy Press nearly qualifies -- however, after beating him, it's revealed that his LoadBearingBoss nature is the only way to get to the [[TrueFinalBoss final final FINAL final boss]] chamber.
* Parodied in ''VideoGame/Stinkoman20X6''. The boss of the [[UnexpectedGameplayChange Darius-style]] level -- where all of the {{Mooks}} are generic sea-life or robots that resemble them -- is described in the manual (which initially had no picture of it) as "a small and speedy octopus or squid."[[note]]It's actually a robot gangster.[[/note]]
* ''VideoGame/TrueCrimeStreetsOfLA'':
** The first game has a whole chapter called House of Wu made of this. You went to investigate a Triad building. Then for no reason you fell down to the basement and fight zombies. The boss of the chapter is [[spoiler:''a huge Chinese dragon that breathes fire and swims around a lava pit'']]. Since the game is a GTA-styled WideOpenSandbox game with a standard cop-show material with no supernatural or weird stuff in it outside of that chapter, many consider it to be entirely out of place. The developers admitted this level was TheArtifact of a prior build and apologized.
** To a lesser extent, the fire-breathing opera boat from the sequel.
* ''VideoGame/{{Klonoa}} 2: Dream Champ Tournament'', as its title suggests, revolves around a tournament. However, the boss stages don't involve actually fighting the other competitors; instead, you have to race them, with your opponents acting like [[TimedMission time limits]] and not otherwise showing up in the gameplay. The actual bosses of the game are just random creatures who appear on the track.
* ''VideoGame/NinjaGaiden II'' (2009) has one at the end of chapter seven. You've just finished dueling a boss who has a prominent part in the storyline, then the plane you are on crashes in the Arctic (or somewhere icy anyway) and a ''giant ankylosaurus made of molten rock'' appears out of the ground to fight you. To add insult to injury, when you defeat the boss, it will explode in what seems to be a {{cutscene}}... but is an actual explosion which will kill you if you're caught in it. And the only way to not die from the explosion is to hold the block button. This basically guarantees that players will die at least once from it.
* After you defeat the BigBad in the arcade version of ''VideoGame/{{Astyanax}}'', who is a ShoutOut to Emperor Palpatine from ''Franchise/StarWars'', complete with "force lightning", you suddenly find yourself in the true final stage, which is a technorganic alien hive complete with eggs and {{Face Hugger}}s. At the end, of course, is the "Queen Alien", which obviously looks like a Xenomorph from the ''Alien'' movies.
* The ''VideoGame/{{Turrican}}'' series. The penultimate or final level would always be a Xenomorph hive straight out of ''Aliens'', complete with {{Face Hugger}}s aplenty. Needless to say, Xenomorphs have nothing to do with the plot of any game of the series.
* ''VideoGame/CastleCrashers'' also does this in the final level. As far as the bosses of TheVeryDefinitelyFinalDungeon go, [[spoiler:although the Necromancer and re-animated Cyclops were seen in the game previously, the burly painter with a lunchbox for a head who attacks by painting monsters that were ripped straight from {{Website/Newgrounds}} was not.]]
* ''VideoGame/AlienSoldier'' has "[[WordSaladTitle Wolfgunblood]] [[http://www.bogleech.com/aliensoldier/as-horseman.gif Garopa]]". It's a [[NinjaPirateZombieRobot cyborg cowboy wolf]] with a [[MoreDakka machine-gun]] ArmCannon that rides on a MechanicalHorse. No explanation is given on why it's there.
* ''VideoGAme/TheGuardianLegend''[='=]s FinalBoss, "It", appears out of nowhere in outer space after the Naju planetoid has been destroyed. Other out-of-place bosses are the "glider", which is actually an enemy from ''VideoGame/{{Zanac}}'', and Teramute, a ''dragon'' that is only encountered in one corridor of the Forest area.
* ''Franchise/{{Castlevania}}'':
** ''VideoGame/CastlevaniaLordsOfShadow'' has the final boss abruptly turn out to be [[spoiler:{{Satan}}]].
** After all the strife and struggle of reaching the end of ''VideoGame/CastlevaniaJudgment'', the player finally faces the mastermind behind the events of the game... [[spoiler:The Time Reaper]]. Granted, he reveals that a villain from ''VideoGame/KidDracula'', [[spoiler:Galamoth]], had sent him from [[spoiler:[[{{Disney/Aladdin}} TEN THOUSAND YEARS]] in the future]] to the past to alter history and make him replace Dracula as the Dark Lord, but there was no buildup to his identity other than he was messing with the timeline, and after he is defeated, he is never brought up again.
* ''{{VideoGame/Contra}}'':
** In ''Shattered Soldier'', the TrueFinalBoss, the Relic of Moirai, is one. Supposedly, he's some ancient EldritchAbomination [[SealedEvilInACan in a Can]], and while it comes out of nowhere at the last second, the whole reason the aliens have been attacking Earth for years was because they are Jovians and we took the relic from them (and the shadowy conspiracy government covered it all up). They were just trying to get it back.
** In ''Super C'', the FinalBoss is a weird techno-organic GiantSpider with a woman's face (nameless in the US version, but called Shadow Beast Kimkoh in Japan) that shoots small spiders at you. This enemy appears as a MiniBoss in later games.
** The TrueFinalBoss of ''[=ReBirth=]'' also qualifies. What is that thing? It looks like an organic ball that attacks you by throwing garbage and debris at you.
* ''Franchise/{{Metroid}}'':
** ''VideoGame/MetroidOtherM'' includes a bolt-from-the-blue BonusBoss of the epilogue chapter, Phantoon. Why he's fought, how he's alive again after being defeated in ''VideoGame/SuperMetroid'', and what he had to do with anything on the Bottle Ship is never ever explained. For a game notorious for its long, redundant expository monologues, it's ironic that it clams up during one of the few times an explanation is actually needed.
** The 3DS re-imagining of ''[[VideoGame/MetroidIIReturnOfSamus Metroid II]]'', ''[[VideoGame/MetroidSamusReturns Samus Returns]]'' adds a surprise boss following the original FinalBoss, and that is [[spoiler:Ridley. Despite being Samus's [[ArchEnemy most hated enemy]] throughout the rest of the series, Ridley does not get any build-up or foreshadowing to his sudden appearance.]]
* Some of the bosses in the ''Franchise/ResidentEvil'' series qualify:
** [[MiniBoss The first Garrador (Blind Slasher)]] in ''VideoGame/ResidentEvil4'' is a little out-of-nowhere as well. While the other three are there as part of ambushes, the first is randomly imprisoned in a basement just to give a short boss fight before you can pull the lever to get through the hallway upstairs. [[FridgeLogic Which also raises a number of questions about what the Ganados expect to do to get through that hallway]] [[InsurmountableWaistHighFence besides squeezing or climbing over the statues spewing the fire]].
** In ''VideoGame/ResidentEvil3Nemesis'', the primary boss is, well, [[ExactlyWhatItSaysOnTheTin Nemesis]]. However, twice in-game, you are attacked by Gravedigger, a Film/{{Tremors}}-esque giant worm, which shows up with zero fanfare besides an earth tremor, and a shed skin in an entirely optional area and is never spoken of again.
** ''[[VideoGame/ResidentEvilCodeVeronica Code: Veronica]]'' has a similar giant worm called the Gulp Worm, and fighting it is optional [[spoiler: as Claire. With Chris, there's no other way, you ''have'' to kill it]].
** Most of the creatures in the original ResidentEvil and its remake are this if you think about it. The Yawn gets foreshadowed by Richard, but if he's dead by the time that you reach him, then it comes as a huge surprise. The Web-Spinners just show up in the residence, same with the adders and hornets. The crows can attack you if you check on Forest's corpse without Barry, or if you press the wrong button in a certain puzzle room. The hunters get a short intro scene, but there is no mention of their existence before hand. The Chimera get a dedicated file to them, but it's after you've already run into a half a dozen of them. Really, the only creatures with an undisputed foreshadowing are the zombies, the Cerberus', Plant 42, the Neptunes, and the Tyrant, the last two of which are the only two with a dedicated holding cell.
** In ''VideoGame/ResidentEvil5'', why exactly was Wesker keeping a GiantEnemyCrab in the giant rotating elevator of his underground base? (Chris actually theorized that Wesker sent it to kill him and Sheva).
** Centurion, the giant centipede, in ''VideoGame/ResidentEvil0''. At least its scorpion cousin Stinger was documented in a file you can find right before battling it.
** ''VideoGame/ResidentEvil2'' gives us a giant mutant crocodile that is fought in the sewers. It has no foreshadowing at all and due to the limitations of the Playstation graphics, the crocodile looks more like a normal croc that just grew huge. ''VideoGame/ResidentEvilTheDarksideChronicles'' gives the mutant croc a makeover and it looks more like a zombie crocodile, but it still retains no foreshadowing.
* ''VideoGame/StarFox1 '' has an alternate FinalBoss that is completely random. After going through a secret level that made NO sense, you fight [[spoiler:a Slot Machine that can only be beaten by getting Triple 7s on it.]]
* Every single boss in ''VideoGame/GunstarHeroes'' and its sequel embodies this trope. Case in point: the board game level, which features a giant face named Melon Bread, a bunch of little slime men that swarm you and only have 1 HP each, a giant gumdrop that summons clones that explode for no reason, and a teddy bear that can be defeated by being run over by a car.
* ''Franchise/MegaMan'':
** ''VideoGame/MegaMan3'' has Doc Robot using the powers of the Robot Masters from ''VideoGame/MegaMan2'' after you beat the initial eight. There's no explanation for what he's even doing there in the first place, nor do we ever really get one.
** Sunstar from ''VideoGame/MegaManV'' is very out-of-nowhere. After spending most of the game with the Stardroids as the BigBad, then having it be [[HijackedByGanon Wily behind it all]], it's very bizarre to have the FinalBoss be a doomsday weapon never even hinted at throughout the game and with no reason to be there ([[AllThereInTheManual unless you read some books saying Wily found him alongside the Stardroids]]).
* ''VideoGame/MuramasaTheDemonBlade'' features a giant centipede attacking a building. Granted, it's actually a creature from the Japanese Mythology (the Oomukade if you want to know), but the story at that point indicated you were about to face off against a human antagonist instead.
* In ''VideoGame/DeadSpace'', the bosses are usually given some sort of buildup; you find Doctor Mercer's notes on the creation of the [[ImplacableMan Hunter]] before you actually fight it (and after you freeze it, Mercer will start to show up again shortly before the Hunter thaws), you spend an entire level trying to make a poison to kill the Leviathan ([[ButThouMust but it doesn't work so you just have to shoot it a bunch of times]]), and the HiveMind is alluded to several chapters prior to fighting it. However, the Slug is given zero foreshadowing. You get "Isaac, there's something blocking our communications" and have to man a giant gun in order to knock it off the antenna.
* ''VideoGame/DeadSpace2'' has [[http://deadspace.wikia.com/wiki/The_Tormenter The Tormenter]] which just turns up after Isaac falls though the ceiling (Isaac had spent the last two and a half levels running from a human gunship).
* In ''VideoGame/PrinnyCanIReallyBeTheHero'', once you reach the Flavor Sage and everything suddenly seems to be going smoothly, the aforementioned Flavor Sage commands the random giant padlock behind him to turn into the Chefbot-9000 and attack the prinny in order to make the Ultra Dessert. The lead character even lampshades how incredibly random this is.
--> '''Prinny''': Nine thousand?! Why does this thing even exist?!?!
* ''VideoGame/RunLikeHell'' had a problem with this, where you will face off against [[spoiler:Niles just after Nick sets the reactor to explode]], but after this awesome battle, you face off against a weak spider-like member of the race as the last boss which is nowhere near as lethal or as bad as the last boss you faced, and he just sort of appears out of nowhere as if they weren't sure what to do for a final boss. To be fair, the series was ended on game one and it was intended to be a trilogy.
* Every boss in ''VideoGame/SuperStarWars'' is a Giant Space Flea From Nowhere, including the Jawas' lava monster, a giant womp rat, and a mech in the Death Star. ''Super Empire Strikes Back'' was somewhat good about bosses making sense (giant probe droids aside), but then ''Super Return of the Jedi'' includes a boss fight with EV9D9 (Jabba's torture droid) in an Ewok Village, and a green fire-breathing tiger thing. What makes this an JustForFun/{{egregious}} example, though, is the fact that they tend to use these ''even when there was a real boss from the movies that would make more sense''. For example, in the Cantina Fight, there's a random giant dinosaur alien in place of simply making Greedo the level boss; there's a couple of Greedo-like mooks, but that's it.
** The boss in question is a living version of the Dejarik piece R2-D2 uses to beat Chewbacca in the movie. Still a bit of an odd choice.
* The Kraken in ''[[VideoGame/GodOfWar God of War II]]''. The beast suddenly appears after Kratos defeated [[spoiler:the Last Spartan]] and its existence was not hinted at all prior to this. It is believed that the Kraken was accidentally awakened by Kratos when the Phoenix is set free or as a trap placed there by the Sisters of Fate as the final guardian to prevent anyone from reaching them should someone awaken the Phoenix .
* ''[[VideoGame/GodOfWar God of War III]]'' has you battling in various boss fights against gods, mythic characters, and even [[spoiler:a Titan]]. After the last boss in the previous sentence, the next boss is[[spoiler:... a giant scorpion who happens to live in the area you're exploring.]] True, it's hinted at by a newly appeared enemy type that hasn't been seen before and some notes on the ground in the area, and said boss is carrying an artifact you need to progress... but after all the epic previous battles, it seems a step down.
* ''VideoGame/TwistedMetalBlack'' combines this with a subversion of TheGuardsMustBeCrazy. The FinalBoss is a military helicopter that shows up to end your rampage.
* A notable subversion in ''VideoGame/KirbySuperStar'': The final bosses of ''Milky Way Wishes'' are this unless the player watched its introduction sequence. However, in the original UsefulNotes/SuperNintendo version, the introduction sequence was both optional and [[GuideDangIt not indicated to even exist]], meaning many players probably wondered what was going on at the end of the game. This was corrected in the [[VideoGameRemake DS remake]], where the introduction was automatically played.
* It's explained that ''VideoGame/{{Bayonetta}}'' and her entire clan of Umbra Witches are often accosted by Angels who their Demon contractors would love as sacrifices, and the whole game takes place during what can be seen as an entire ''revolution'' for the angels, so at no point can an angel appearing to fight Bayonetta be strange. The real Space Flea from nowhere is the one enemy of the game that ''isn't'' an angel... It's a machine. The Occult Device: The Golem. It's not mentioned at any point in the story, and its backstory explains that it was created by both the Lumen ''and'' Umbra clans. Because the weapon was built by Witches and Sages, it makes it even stranger, still, that it appears in Paradiso, the world of the Angels, of all places. It's just... there. Slamming itself into random walls throughout the level and eventually fighting Bayonetta properly at the end, but it gets no mention in the plot, and the controller of this device [[spoiler:or of the one that appears in [[VeryDefiniteFinalDungeon A Tower To Truth]]]] is never revealed.
* The Rogons in ''VideoGame/EVOSearchForEden'' are a race of intelligent fish who are harming the whales, and the player is tasked with taking them down. Absolutely none of this is foreshadowed in any way, nor do the Rogons have any relevance to the rest of the game.
* In the Japanese Famicom version of ''StarWars'', you run into Darth Vader a ''lot'' in the game. He shows up very early on, starting in the Sandcrawler for some reason. When you hit him, he turns into a scorpion. This actually happens throughout the game, and Darth Vader will transform into different creatures depending on the level. The ''real'' Darth Vader is actually fought twice.
* In the relatively down-to-earth ''Franchise/JamesBond'' game ''VideoGame/EverythingOrNothing'', one of the early levels ends with Bond in a helicopter attacking a hidden base that rises out of the Nile that wouldn't look out of place in a ''StarWars'' game. Never gets mentioned again.
* The PC game for ''[[VideoGame/HarryPotter Harry Potter and the Philosopher's Stone]]'' has Harry escaping from the astronomy tower, pursued by Filch, to a Quiddtich game, and then randomly under the trap door -- leading to the final battle with Voldemort. The game skips about half of the book and movie.
* ''Treasures of the Deep'' has a level titled [[IncrediblyLamePun "Montezuma's Revenge"]], where you explore the underwater ruins of a Aztec Temple to find two pieces of Montezuma's lost treasure. After getting the first treasure, entering the room with the second brings you up close and personal with [[spoiler:a giant reptilian monster with webbed underarms]]. The worst you faced up until this point were some angry crocodiles and booby traps.
* ''VideoGame/ComicJumper'' has Benny, a walking, talking ''Film/TotalRecall1990'' reference (complete with giant drill machine) show up in the last Silver Age level, followed by the giant photorealistic head of a Japanese kid in the first manga level.
* ''Anime/AfroSamurai'' the game has a few of these. On the Bridge level, the player finds themselves taking on several mini-bosses directly out of left field, with most of them immediately followed with an IndyEscape over a collapsing bridge. The first is an overconfident Big Mook who you later see mass-produced with a few standard mooks. The second is a band of 5 samurai aptly dubbed 'The Wild Five', who are troublesome but easily dealt with. And the last and most ludicrous is explosively introduced as Afro walks away from the fight with the Wild Five with no warning what-so-ever. A flying robot (that looks akin to FLCL's Canti) smashes through the bridge beneath Afro's feet and pulls him into the sky for a midair-freefall-boss-fight of badass proportions. The player's navi guide in the shape of Afro Samurai's Ninja Ninja (Creator/SamuelLJackson) even presses the unexpectedness further by turning to the player (camera) and saying just how unexpected it was. "Did you just see that sh**?!... You go keep an eye on that fool, I'm gonna go get some coffee."
* In ''VideoGame/{{Psychonauts}}'', the StepfordSuburbia of the Milkman Conspiracy is suddenly interrupted at two points where demons called Nightmares pop out of the ground and drag you to [[PlanetHeck a stage full of fire and darkness.]] [[WhatCouldHaveBeen They were originally going to be part of Milla's mental world]], but were moved because it didn't make sense for a boss fight then either.
* Played straight and then lampshaded in ''VideoGame/KidIcarusUprising''. At the end of Chapter 8, Pit prepares to take on the captain of the Space Pirates in order to retrieve the three Sacred Treasures he used to defeat Medusa in the first game, when suddenly a giant [[KrakenAndLeviathan Kraken]] leaps out of nowhere and [[BaitAndSwitchBoss eats him]].
-->'''Palutena:''' "A Space Kraken?! Well that came out of nowhere!"
* In ''VideoGame/DeadToRights'', at the end of the warehouse level, Jack Slate finds the guy he was chasing (Gopher) killed, and the person who killed him is... some random hulking dude with a crossbow called Longshoreman X who you then fight in a boss battle; this guy has zero build-up, and there's no mention afterwards as to who he was or why he killed Gopher.
* ''VideoGame/MetalGearRisingRevengeance'' has the Metal Gear EXCELSUS, piloted by Senator Armstrong. Even more-so is [[spoiler:Armstrong himself, who afterwards bulks up and induces TheWorfEffect upon Raiden]]. Even the Mission Control is shocked, since if you talk to Kevin beforehand, he'll note that [[spoiler:there's nothing they dug up on Armstrong that could have suggested that he was in any form a physical threat (aside from the fact that he was in the Navy but didn't see any action)]].
* The FinalBoss of ''VideoGame/JourneyToSilius'' is an oversized SkeleBot9000, a holdover from the game starting development as a ''Franchise/{{Terminator}}'' LicensedGame.
* ''VideoGame/TransformersConvoyNoNazo'' isn't quite an example, but the game ''does'' still have an example in the form of a giant Decepticon logo that's fought more than once throughout the game.
* In the second ''Film/TheBlairWitchProject'' game, ''The Legend of Coffin Rock'', the final boss is something which looks like a cross between a lizard and a bull, and named "Schnell Geist". The only foreshadowing for this is one book in the library near the beginning of the game which describes a local folklore creature called "Snallygaster". Those are different names for the same thing, although the game never gives you that connection. It actually comes from real folklore for the Maryland region.
* ''VideoGame/TheAngryVideoGameNerdAdventures'' has an unexpected appearance by Film/TheGiantClaw, which the Nerd had never mentioned in his prior videos.
* The arcade classic ''VideoGame/{{NARC}}'' has you fighting human criminals (though outlandish ones) and attack dogs through the entire game. Then you fight the final boss, Mr. Big, who is a disembodied big giant head sliding around on some sort of high-tech pedestal. Damaging him first causes his sunglasses to break off, which will allow him to shoot fire from his eyes. More damage will turn him into a skull slithering around at the end of a tentacle-like spine, spraying you with an endless supply of detached tongues.
* ''VideoGame/TheBindingOfIsaac'':
** Some of the {{True Final Boss}}es fall into this category. While the final fight against Mom makes sense, as does [[spoiler: Mom's Heart in The Womb to an extent]], the latter is eventually replaced by [[spoiler: It Lives]], which makes less sense. The Halloween update adds Sheol and [[spoiler: Satan]], which make some degree of sense, but then ''Wrath of the Lamb'' adds two more space fleas: [[spoiler: Isaac himself and JokeCharacter [[MyNameIsQuestionMarks ???]]]]
** The first new FinalBoss of ''[[UpdatedRerelease Rebirth]]'' is a space flea as well. Apparently the next logical step after fighting [[spoiler: Satan]] is to fight [[spoiler: The Lamb, some random demon found in the Dark Room.]] And after him, at the very VERY end we get [[spoiler:Mega Satan. It's just Satan again for no given reason]].
* In ''VideoGame/WonderBoy'', the bosses of the two Master System-exclusive areas (4 and 8) have a unique design and theme music, attack with lightning instead of fireballs, unlike all the others, and have no apparent relevance in the story.
* The [[StupidJetpackHitler Nazi Frankenstein]] in the Prague level in ''VideoGame/IndianaJonesAndTheEmperorsTomb''. Granted, he is holding a PlotCoupon, but he comes from out of nowhere with no explanation, no backstory, and nothing to suggest ThoseWackyNazis were engaging in anything other than bog-standard Nazism, not SuperScience. Indy doesn't even bat an eyelash as if throwing acid at an 8' tall fireball and furniture-throwing Super-Soldier is part and parcel with being an [[AdventurerArchaeologist archaeologist.]]
* ''VideoGame/BloodRayne2'' had the Unraveler. In a game about a {{Dhampyr}} [[ActionGirl assassin]] fighting a cult of vampires lead by her [[ArchnemesisDad evil vampire father]], Unraveler is a creature whose origin and nature are not explained into detail and doesn't seem to be related to vampires in anyway, but the heroine just runs into it when storming the villain headquarters. The only things we ever know about it is that [[EvilSmellsBad it smells really bad]] and its picking up a fight with the BigBad's minions.
* In ''VideoGame/PrinceOfPersiaWarriorWithin'', a giant Griffon appears out of nowhere to fight the Prince midway through the game. While its presumed to be one of the many sand monsters created to guard the Island of Time, its radically different from all other enemies fought at this point and it gets defeated with nary ceremony.
* In ''VideoGames/HercsAdventures'' for the {{PlayStation}}, you run into the Martians from VideoGames/ZombiesAteMyNeighbors in an early stage. The game was written by the same people, so it's just an EasterEgg. But then you fight the final boss, [[EverybodyHatesHades Hades]] and in the end...Hades is a robot controlled by the Martians. Where's the real Hades? Was there a real Hades? Was he replaced? If Hades was always a robot, did Persephone or the other gods know? These questions will never be answered as the game ends there.

[[folder:Role-Playing Games]]
* Duriel, the BaitAndSwitchBoss at the end of the second act of ''VideoGame/DiabloII''. The player had been led to believe that Baal would be the final boss of the second act, and nothing in either the sound files or the manual of ''Diablo II'' says anything about Duriel. The only way the player would know who he was is from reading the ''Diablo 1'' manual
* The ''Franchise/FinalFantasy'' series has a bunch of them, some of which act as the FinalBoss directly after defeating TheHeavy.
** ''VideoGame/FinalFantasyIII'' contains a prototype for these types of enemies in Cloud Of Darkness, a barely-explained cosmic force who pops quite literally out of nowhere to fight you after you beat BigBad Xande. Unlike most of the later examples of this trope, however, the Cloud of Darkness actually has a good deal ''more'' screentime than Xande, who only appears in person very briefly at the end of the DiscOneFinalDungeon.
** ''VideoGame/FinalFantasyIV'':
*** Zeromus, the final boss. He had only a vague connection to the plot, being the hatred of the main villain given form, and seemed to be present largely to provide a massive, intimidating final boss -- which Zemus [[TheManBehindTheCurtain very much wasn't.]]
*** Calcabrina, the living dolls, though the sequel, ''VideoGame/FinalFantasyIVTheAfterYears'', not only ties them into the plot, they even become playable.
*** There's also Lugae. Halfway up a tower which you already know contains a boss you'll have to fight, you run into a guy in a lab coat with Einstein hair, who fights alongside an '80s Frankenstein's monster and then turns himself into a gangly zombie. And apparently survives both battles.
** Ultros from ''VideoGame/FinalFantasyVI'', the most amusing Space Flea ever. He's a giant purple octopus who comes out of nowhere and attacks you (in the [[{{Woolseyism}} Super Nintendo translation]], he claimed to want to eat your party, which was at least ''some'' sort of motivation, but this wasn't in the original Japanese, nor the Game Boy Advance version, where he just attacks you and that's that). When you give him a beating, he escapes and later comes back to wreck the opera you're attending, along with other situations, for revenge. It's even funnier if you pick Gau and Cyan to go to the opera house. Why? Because this means your party is made up of members Ultros has never met before, and thus he's plotting "revenge" against a pack of total strangers. He makes a cameo as a boss in ''The After Years'', and the collective reaction of the party is something along the lines of "what the hell was that about?"
** Ultros also makes an apparition in ''VideoGame/FinalFantasyXIV''. Apparently, the thaumaturges of Ul'dah summoned him to their world by mistake. At least his role in the plot gets some build up, as he needs to work at the coliseum in order to repay the heavy debt he piled up by drinking at the local bar.[[note]]This is a Shout Out to Final Fantasy VI, in which he got roped into working at that game's Coliseum for the same thing.[[/note]] Aside from that, citizens of Ul'dah seems to be unfazed to see a purple pervert octopus [[MoreTeethThanTheOsmondFamily with a lot of teeth]] in their city.
** Atma/Ultima Weapon also fits this. He's the boss of the DiscOneFinalDungeon, and enters battle delivering a BadassBoast about how ancient and powerful he is while a new, more foreboding boss theme begins to play. Aside from an off-hand mention from a single random NPC much earlier in the game, he's never mentioned beforehand and the party doesn't give him any thought afterward.
** Siegfried/Ziegfried. He is a joke boss on the Phantom Train, also appearing in [=WoR=] Cave of Figaro and the Coliseum, who has no relevance to the story whatsoever. He is a "legendary" thief who has some relation to Ultros (this is not explained in detail), but despite being "legendary", the only two characters that mention him are himself and Ultros. It is probable that the version on the Phantom Train is actually an impostor, but this just adds to the randomness.
** Necron in ''VideoGame/FinalFantasyIX'', predominantly because he is also a ''final'' boss who appears suddenly and has no prior lead-up within the context of the storyline. Fans have come up with many EpilepticTrees concerning his relevance and existence, but nothing definitive is ever provided, and his existence is not even mentioned during the ending sequence. Even worse, he directly followed Kuja, a ''legitimate'' BigBad and one of the more popular villains in the series. One is left wondering if the designers wouldn't have been better off making Kuja a SequentialBoss.
** While we can't very well say that ''all'' the [[BonusBoss Notorious Monsters]] in ''VideoGame/FinalFantasyXI'' fit here, as most aren't part of a storyline, and others are actually mentioned before you meet them, there's not much mention of ''[[http://wiki.ffxiclopedia.org/wiki/Snoll_Tzar a giant angry snowball the size of a van with teeth]]''. Most of them are at least thematically consistent with the areas they come from, though.
** On a less-major level, several minor bosses throughout the series are just random monsters that turn up and fight you for no real reason, to ensure you are levelled properly.
*** ''VideoGame/FinalFantasyVII''[='=]s Schizo, a strange two-headed dragon who showed up ''immediately before another (actually plot relevant) boss fight,'' just to prove it wasn't even there for level structure reasons. It was just kinda there.
*** There's also the Red Dragon in the Temple of the Ancients. First, Sephiroth reveals his master plan to become one with the Planet. He flies off, then suddenly, the room that this took place in starts shaking and the lights begin to dim. Cloud wonders if this is Sephiroth's doing, but the latter says it's not him. It was actually the Red Dragon that got absolutely no prior build-up, at all. When you defeat it, Cloud immediately asks where Sephiroth went and the Red Dragon is ''never'' brought up again.
** Several bosses in ''VideoGame/DissidiaFinalFantasy'' have no plot reasons for their encounter with the heroes, they just appear and decide to challenge you. The Warrior of Light's battles with Garland, Ultimecia, and the Emperor are the most prevelant; he's searching for his Crystal, the enemy appears and taunts him, he replies ShutUpHannibal and they fight.
%%** ''VideoGame/FinalFantasyXIII'' has possibly the most literal example out there: at one point, the party must fight an improbably huge robot bug that has somehow appeared on the satellite you're on. No explanation is ever given for what it's doing there.
* Qem in Iron Twilight jumpscares you and then just fights you. Not to mention, he makes a grid that's impossible to escape out of FIRE and traps you inside it for the remainder of the battle. [[TennisBoss This means you have to press enter on the crystals to send them flying back at Qem to damage him.]]
* ''VideoGame/DragonQuest'':
** ''VideoGame/DragonQuestII'' had one of the earliest examples of the Giant Space Flea from Nowhere final boss. After defeating the BigBad of the game, Malroth (Sidoh in Japan and the UsefulNotes/GameBoyColor version), who he turned out to serve and worship, appears out of nowhere to be the final boss. This was particularly nasty in the US version, as absolutely ''nothing'' hinted at his presence aside from a minor quest item named "Eye of Malroth" (and the [[TrailersAlwaysSpoil box art]]; look closely at the mural behind Hargon), and he is infinitely harder than the game's BigBad, Hargon, mostly because he randomly casts Healall to set his life back to full whenever he feels like it.
** Bjorn the Behemoose from ''VideoGame/DragonQuestV'' can appear to be one (emphasis on the Giant, he's the size of a mountain and is fought from the top of a tower) via accidental SequenceBreaking, as the key he drops is needed for the final dungeon but he can be fought just after three-fourths of the way in the game.
** Mortamor of ''VideoGame/DragonQuestVI'' gets namedropped pretty late in the game as well, with his evil being OffstageVillainy, via his minions.
* ''VideoGame/StarOcean'':
** Happens in the original game, after a VictoryFakeout no less. Just when you think you've saved the day, all of a sudden, there's this Jie Revorse jackass to deal with, and there's absolutely no lead-up into this. The PSP rerelease at least has a minor rewrite in order to link him to the main plot. This was one of many unfortunate side effects of half the game being DummiedOut for space reasons.
** The third game features literal Giant Space Fleas, literally from nowhere, which invalidate entirely almost everything that happens previous to their arrival. Not a technical example of this since the entire second half of the game involves dealing with them, but considering the profound implications their arrival has on the ''entire series'', the fact that they happen with absolutely no warning has gone so far as to [[BrokenBase break the base]].
* In ''VideoGame/{{SaGa Frontier}}'', Emelia's final boss is an actual gigantic Mecha Shiva that drops down from the roof of the church where Emelia is pretending to have a wedding ceremony with the party in lieu of her dead boyfriend. WordOfGod explicitly states that there's no relationship at all between this creature and the BigBad. It seems to exist solely to provide a final boss to the character arc.
* The ''Franchise/{{Lunar}}'' games tend to develop villains rather well, so instances of this trope stand out. Giant Space Fleas are more common in the Sega CD games, and get {{Discussed|Trope}} in the elaborate StrategyGuide for their remakes. The developers chose to remove several examples that could distract from the main narrative, while putting more emphasis on some of the baddies that ''did'' make sense.
* ''VideoGame/SkiesOfArcadia'' has quite a few of these.
** An overweight, acid-spewing rabbit, a giant robotic penguin with a death-ray, a floating tortoise that could make itself invincible, and a cockatrice-esque giant bird all appeared suddenly, were dispatched by the heroes, and died without comment from anyone.
** There was a gigantic green blob in the game's sewer level (the aforementioned "acid-spewing rabbit"). What made him twice as bad was that not only does he come from nowhere, but after beating him, you ''immediately'' have to fight a boss that IS related to the story. That sequence sticks is one of the toughest parts of the entire game, partially because it happens so early and your healing options are very limited.
* ''VideoGame/MarioAndLuigiSuperstarSaga'' has a couple:
** Trunkle, a rock-tree-creature who suddenly appears at the end of the desert section to menace the princess for a distinctly nonspecific reason. If you go to that area before Peach is with you, Trunkle will be sleeping there; you can infer she woke him up and he got angry.
** Before Trunkle, there's a part of the game where you save the queen by having her drink a legendary soda. The main boss of that section... [[WidgetSeries is the soda. The guy who created it made it able to defend itself.]] [[BigLippedAlligatorMoment No one mentions this again.]]
** Before the aforementioned soda fight, there's a moment where a Wiggler is sitting in a hole in a hedge that Mini Mario can fit through, so the Bros. jump on it to make it go through the hole. Then, once you make Mario mini and try to enter the hole, Wiggler pops back out with its trademark red angry face and you fight. Wiggler never shows up again.
** And even before the Wiggler fight, in the area that ties the main overworld with Chucklehuck Woods, there's a moment where you have to go through a maze of barrels where you can barely even see the Bros. Once you get to the end of the maze, the bro in back has been replaced with some green guy who promptly runs ahead once the bro in front realizes that the man behind him is not his brother. Once Mario and Luigi enter the next room, the green man (whose name is Popple) is talking with his sidekick, Rookie ([[spoiler: Bowser had gained amnesia]]), and suddenly realizes the Mario Bros are watching, and engages a fight.
*** The next 2 fights with Popple are also out-of-nowhere. The second time, [[spoiler:after defeating Cackletta, the Beanstar falls through the floor into the basement, and once the Mario Bros get down to the basement, they find Popple and Rookie, the former claiming he managed to "summon" the Beanstar]]. They fight again. The third time, [[spoiler:Mario and Luigi are looking for the pieces of the shattered Beanstar. One of them is in Chucklehuck Woods, and when they get close to the location of the star piece, a cutscene begins where Popple is trying to get the piece out of a statue, and the Bros. corner him]]. They fight again.
* ''VideoGame/MarioAndLuigiPartnersInTime'' generally gives each boss some relevance in some way. This is not the case with Commander Shroob and [[spoiler: Shrowser]]. Commander Shroob, who just shows up to make sure the Toad Town/Star Hill area has a boss fight. No one mentions him before or after, and despite being affiliated with the villains, there's no other sign of him outside of his boss fight. [[spoiler:Shrowser is the ghost of The Elder Shroob Princess inside Bowser (jeez, a lot of things keep going inside Bowser)]].
* ''VideoGame/MarioAndLuigiDreamTeam'' has a couple of these:
** Mammoshka. You never know there's a powerful guardian on Mount Pajamaja unless you speak to one of the trapped Pi'illos on the mountain, otherwise you won't until you literally see it in the cutscene just before the fight. It's supposedly legendary... but no one ever mentions it except for said Pi'illo and the Massifs about 30 seconds before the battle.
** Earthwake. One minute you're walking through Dreamy Wakeport trying to free the Bedsmith from some Nightmare Orbs, next minute that Pi'illo Collector guy appears and warns you of a terrible guardian that attacks anyone who hits the nearby ! block (and you see a save block nearby). And even after hearing this, you most likely don't expect the building you're standing on to fly into the air, an alarm klaxon to sound, and a HumongousMecha made of buildings from the background to form and try to kill the Mario Bros.
** Pi'illodium. You don't know about this ancient Pi'illo security system until it literally appears and someone asks what it is.
* On the whole, ''VideoGame/SuperMarioRPG: Legend of the Seven Stars'' is pretty good about making sure all its bosses are either connected to the plot in some way or at the very least foreshadowed. However, nothing whatsoever explains what happens when you [[SpeakNowOrForeverHoldYourPeace break up the Princess's wedding to a minor villain]]: The chefs who prepared the wedding cake get upset that their work will be unappreciated, so they attack you. Then, the wedding cake inexplicably comes to life and uses its inexplicably vast magical powers to try and kill you for some inexplicable reason, and Mario doesn't even (technically) defeat it; once the cake's HP is worn down low enough, the minor villain interrupts the fight and eats it. Similarly, the boss for the 3rd star piece has absolutely no connection with the plot and fights the party simply because they don't know who he is.
* ''VideoGame/PaperMario'' series:
** Smorg from ''VideoGame/PaperMarioTheThousandYearDoor''. While its individual components do appear in one room in an abandoned train station where [[CreateYourOwnVillain you bashed them in the face to get to a switch]], it gave no indication that they would be able to amass together to create some giant animal made out of sentient balls of lint. The only apparent reason it exists is to give the chapter a boss fight that isn't [[spoiler:Doopliss]].
** There are also the three giant Bloopers in the first ''[[VideoGame/PaperMario64 Paper Mario]]''. They serve no purpose in the game's story, and just appear without warning while you're exploring the sewers under Toad Town screaming "BLOOPER!" in huge text, and are not mentioned by anyone before or after fighting them. Although, by the time you see the Super Blooper (the third one), the shock has all but worn off.
** There's also Kent C. Koopa, who you encounter on Pleasant Path after a certain point in the plot. He literally shows up from out of nowhere to block your path for no good reason. You can either fight him or pay him a temporary toll, and while the sewers have a pipe to Koopa Village, Kolorado, who wants to go home, doesn't appear to know about it, and Kent's good Star Points if you're prepared to throw down, so... (Actually, there's a sign in the Mushroom Kingdom that foreshadows his existence. Make sure to read both sides of it each chapter).
* {{Lampshaded}} in ''VideoGame/{{Suikoden}}'', where encountering a random boss enemy that is not referenced before or after causes one character to exclaim something along the lines of "What the hell!?" before the fight. It's also played straight with a few other encounters.
** In ''VideoGame/SuikodenIV'', at the climax of the game, you fight [[spoiler:a [[WhenTreesAttack Giant Space]] ''[[WhenTreesAttack Tree]]'' [[WhenTreesAttack From Nowhere]]. [[ItMakesSenseInContext It's actually explained]] in the game's {{Backstory}} -- and [[VideoGame/SuikodenTactics the sequel]] clears things up for those who didn't piece things together on their own -- but still, it's very much a [[BigLippedAlligatorMoment WTF moment]] at the time.]]
** Almost every boss that isn't a human character in ''VideoGame/SuikodenV'' falls into this category. [[spoiler:Even the ''final'' boss of the game, the Sun Rune incarnation, shows up and then dies without a single mention before or after. At no point does the Queen mention that the Sun Rune can do that, none of the villains mention that that's who they're trying to awaken or that that's their ultimate plan... The BigBad just disappears into a cloud of dust right before the battle and '''QUICK BOSS TIME GO'''.]]
* ''VideoGame/KingdomHearts'':
** [[Disney/{{Fantasia}} Chernabog]] literally appears out of nowhere, after you've jumped through the hole in "The End of the World". You don't know who he is, Sora makes no comment about him whatsoever, it's never explained if he's a Heartless, what connection he's got to Xehanort or ''why'' he's even there, he's the only boss who doesn't get an entry in Jiminy Cricket's journal, and he's never mentioned again. It's as though the developers just thought it would be a disservice not to include one of the most impressive Disney creations, even if they had to just drop it in without so much as a single word of context. It's just plain RuleOfCool (and copious RuleOfScary). Apparently, when they were asked about him being in the game, the devs stated that Chernabog was originally going to be the final boss, as he was supposed to be the source of all of the Heartless. Unfortunately, having a Sephiroth proxy seemed cooler, so Ansem's battles were put in. That's why they're so relatively easy compared to his battle.
** There's a brief reference to Bald Mountain... in Traverse Town. Which you may never actually notice. And which makes no actual reference to giant demons.
* ''The Granstream Saga'' produces a boss from nowhere. ([[spoiler:But also manages to tie it into the plot while simultaneously nullifying the rest of the point of the game]].) You've happily completed the game's quest across four floating continents to save them from falling into the sea. ([[spoiler:Then you're sucked into a black hole where someone named Demaar tells you that the whole world was an illusion and that you have to fight him to break a hundreds-of-years-long cycle.]]) To call it out of nowhere would be something of an understatement.
* In ''VideoGame/JadeEmpire'', the obstruction of the spirit world at Dirge allowed a being of pure darkness from outside the human and spirit worlds to arrive, which the player must defeat. There is little explanation of what it is or where it comes from, it simply is.
* Nearly every boss in ''VideoGame/{{Mother 3}}''. Notable ones include Master Eddy, an animate whirlpool you fight near Tanetane Island, and the Forlorn Junk Heap, a discarded clayman reinforced with scrap metal. Of course, [[WhatDoYouMeanItWasntMadeOnDrugs considering what kind of]] [[MindScrew game this is]], you really can't complain about weirdness.
* In ''VideoGame/ChronoTrigger'', every boss you fight up until the battle against Dalton [[spoiler:on top of the Epoch]] is more or less relevant to the plot. After that, you have the choice of battling Lavos [[FinalBoss one last time]] or go on several [[SideQuest Side Quests]]. However, one boss fight during the main storyline occurs for no reason. It's the fight against the Mud Imp and his 2 Mudbeasts in the Terra Cave (12,000 B.C.). At the end of said cave, you'll see the 2 beasts standing in your way of entering the Mountain of Woe, then the Mud Imp arrives, yelling "[[YouShallNotPass Yer not gettin' through 'ere!]]" before the battle begins. If you kill the 2 beasts first, he'll eventually [[ScrewThisImOuttaHere run away]]. Whether the Mud Imp dies or flees, it's never explained why he was in your way in the first place.
* ''VideoGame/ChronoCross'' and the Time Devourer. Sure, Lavos is mentioned a couple times in passing ''if'' you go out of your way to read side documents near the end. Schala isn't. But the game already gave two 'final' bosses before this, one at the end of a long dungeon and the prior requiring a long attunement and the entire game having built up to it. But then you fight this giant space-eating glowing thing that merged with Schala somehow and defeat it with ThePowerOfRock? What the hell? Dropping Magus in would have made about as much sense. Hell, Chrono, Marle, and a zombie Lucca would have made about as much sense. And what was with Miguel? ''Why was he a superpowered philosophical fisherman?''
** Most of the bosses in ''VideoGame/ChronoCross'' fall into this category, really. Generally there's a thematic link between boss and area they're fought in, but any fight that's not preceded by a story scene exists solely to give the player another star level.
* ''Franchise/{{Pokemon}}'':
** The roaming legendaries, once unlocked, can be found absolutely anywhere in the world and change location at random. You're just sitting there, training up your Golbat, when -- HOLY CRAP! A RAIKOU!
** In the original games, Moltres also qualifies. Its Ice and Lightning counterparts are found at the end of optional Ice and Lightning dungeons. Naturally, you'd expect find Moltres, the fire bird, in some kind of fire-themed area. Then you find it standing around in a dead end of the underground tunnel leading to the last bosses. It was relocated to a less bizarre area in the remakes.
** In ''[[VideoGame/PokemonXAndY X and Y]]'', you can encounter Mewtwo [[spoiler:lurking in a cave in the Pokemon Village]] after defeating the Elite Four. No explanation is given in-game as to why it's there, other than [[CallBack Gen I nostalgia]] and a halfassed HandWave about the [[spoiler:village being a refuge for unloved Pokémon]].
** Even among legendaries (who tend to be this trope at times), Heatran (who first appeared in ''[[VideoGame/PokemonDiamondAndPearl Diamond and Pearl]]'' is rather random. The guy can be male or female (whereas most legendaries are either [[NoBiologicalSex genderless]] or a OneGenderRace), simply chills inside volcanoes and has no real legend to speak of; at best it was supposedly born after Mt. Stark was created, but this has never been elaborated on since.
** ''VideoGame/PokemonSunAndMoon'':
*** After completing the post-game storyline, walking through the tall grass in [[spoiler:Ten Carat Hill]] has a chance of pitting you against a [[spoiler:level ''75'' Necrozma. In an area where the wild Pokémon are around level 12]]. The only clue you get to its existence is a very cryptic hint that gives no indication of the encounter taking place there, and no real explanation is offered even after encountering the Pokémon in question.
*** Also, [[spoiler:one of the challengers for the Champion title is Ryuki, a LargeHam rock star from another region who specializes in Dragon-types, and that's all we knew of him until his appearence in ''VideoGame/PokemonUltraSunAndUltraMoon.'']]
* The FinalBoss of ''VideoGame/RogueGalaxy'' is a ''very'' odd example of this. For the first two-thirds of the game, Valkog appeared to be the BigBad; after a certain event ([[spoiler:actually reaching Mariglenn/Eden]]), Valkog and his flunkies are suddenly demoted to QuirkyMinibossSquad and you don't expect to even SEE them again. However, once you face off against the supposed new BigBad in a [[OneWingedAngel two-stage battle]], Valkog shows up again...and through a convenient plot contrivance, he and his two flunkies ''and their spaceship'' are transformed into the FinalBoss.
* Erebus, the final boss of ''[[VideoGame/{{Persona3}} Persona 3: The Answer]]''. It ''was'' mentioned in the first game that [[spoiler:Nyx, the BigBad, was being called into existence by the despair and depression of humanity]], but the player was probably not expecting that [[spoiler:those emotions would take the form of a giant, two-headed... thing made of shadow]]. For that matter, the main game's BigBad was also kind of an example, being revealed after 80% of the game was over and never explained beyond wanting to bring about TheEndOfTheWorldAsWeKnowIt.
* ''VideoGame/{{Persona 4}}'' has the TrueFinalBoss, only she is revealed at the very last minute (as in moments before you're supposed to leave town on a bus). This is made more apparent because the true murderer of the case you were trying to solve has already been defeated, as well as the being that was behind him. The plot also winds and swerves in so many directions that spoiling the TrueFinalBoss by itself doesn't really give away anything else.
* In ''VideoGame/DarkCloud 2'' (Or ''Dark Chronicle''), the final boss of the game, at the end of a bonus dungeon, is the BigBad (for no reason) from the previous game.
* Muffet, from ''VideoGame/{{Undertale}}''. She was hired by someone to take the player's soul, but unlike every other boss, she has no direct impact on the plot. On top of that, there are ways to [[SkippableBoss avoid fighting her]]. The reason for this is that she was created as a Kickstarter bonus after the other bosses were finished and the plot solidified, so there wasn't much room to put her in except as this.
** Mad Dummy, too. He appears somewhere near the middle of the game, fights you, then flees and never does anything significant for the rest of your run. His cousin, Napstablook, isn't very important to the plot either, but at least he [[spoiler: plays a part in the Mettaton storyline, and he's the one who saves you from Mad Dummy.]] The odd connection between these three relatively insignificant mini-bosses is that Mad Dummy's battle theme is the remix of Napstablook's theme, while Muffet's theme features remixed parts of Mad Dummy's theme.
* ''VideoGame/LastScenario'':
** A ''lot'' of the bosses in the first game. Some (generally the more human ones) at least merit some acknowledgment by the characters, but others (say, the Viviones) are never mentioned again, even if they [[ThatOneBoss took you a dozen tries to defeat]]. There's also the boss unlocked by beating the game after collecting every hex tile, at which point it's just hanging out on the World Map waiting for you to fight it with no explanation or even a single line of dialogue: [[spoiler: Planetary Consciousness.]]
** In the second game, [=ExitFate=] uses them as well, but at the same time the way characters talk about them will subvert a few by sheer virtue of no longer being unreferenced. A good example is that a lot of the time military strategy or simple day to day operations will be disrupted by these powerful monsters. While it's never clear where they all come from, The game goes out of its way to at least put reasons for them being there. That random giant monster at the end of a tunnel? Turns out it's why nobody used the tunnels anymore. Random dragon in some old ruins? Turns out the excavation team can't do their job anymore because of it. Random magic monster at the end of the forest? Turns out it's there for some reason other than to have a boss fight.
* ''VideoGame/BatenKaitosOrigins'' is particularly infamous for one of these. The game is a double disk, and you switch from one disk to the other right after battling a boss and moving to a new area. You have to save your progress when inserting the second disk, only to be shipwrecked and stranded in a hostile forest instantly and having to battle one of the most ridiculously difficult boss battles in the game (since, most likely than not, your party will be severely underleveled and the boss can heal itself). It ends up being one of the cheapest battles in the game, since it's completely unexpected and thus you'll be unprepared for it. And since you're stranded in a forest and you just saved your progress, you can't go back to raise your characters' level.
* ''VideoGame/BatenKaitos: Lost Wings and the Eternal Ocean''. At one point, you're in a [[BigBoosHaunt ghostly area]] where it's stated that the walls between dimensions is weak. Best way to showcase this? A giant monster bursts out of another dimension, and you fight it back in.
* ''Franchise/DotHack'': The original games were actually decent about its Giant Space Fleas. All the 8 Phases of Morgana may have looked bizarre -- as [=BlackRose=] was oft to point out -- but there was a point where that was expected. Even Cubia was given ample foreshadowing, although his initial appearance at the end of the first game certainly may have been a surprise. The first game ended with a surprise AIDA infection after a battle with Tri-Edge [[spoiler:actually, Azure Kite]]; the second game ended with [[spoiler:Tri-Edge being revealed as the monster hiding in Ovan's arm]], hitherto [[spoiler:thought to be where Corbenik was hiding]]; then, suddenly, in the last game, [[spoiler:Cubia appears]].
* Quite a few of the bosses in ''VideoGame/EternalSonata'' were these. Potentially justified, in that things don't always make sense in a dream.
* ''VideoGame/UltimaIII'' has one in the form of Exodus; not a traditional boss fight to end the game with, but instead, in the midst of a medieval fantasy setting: [[spoiler:a computer into which you must insert four punchcards in the proper order]]. Not exactly what you were expecting, after the first two games, but paved the way for the last-boss-less sequels.
* ''VideoGame/DigimonWorld3'':
** Armageddemon shows up just before you get to fight the BigBad. Every other Digimon boss is foreshadowed by having an overworld sprite; he doesn't. It's debatable whether he's supposed to be a ''boss'' -- the random battle theme is used and it's possible to run from him. [[spoiler:He's also one of three old bosses featured in the final boss battle]]. He's used in a similar capacity in ''VideoGame/DigimonWorldDS'', but this time he gets a line of dialogue and the player's character explaining what he is.
** The main plot of ''Digimon World 3'' also does this. All of the terror in the Digital World was supposedly caused by [[spoiler:the MAGAMI company]]. However, after dispatching all of their head honchos, something called [[spoiler:Lord Megadeath]] shows up and claims responsibility for everything. You are then transported to his orbiting satellite, where you fight him. Absolutely no mention of this character is made until just before that sequence.
* The BigBad of ''VideoGame/{{Anachronox}}'' is not revealed until the very end[[note]]You ''can'' actually see him while on a trip to Sunder.[[/note]], his name is not revealed, nor is anything known about him. It doesn't help that the game was supposed to [[SequelHook have a sequel]].
* The ''VideoGame/ValkyrieProfile'' series has a few, but a particularly odd one is Ull, from ''VideoGame/ValkyrieProfile2Silmeria''. He appears in a brief cutscene establishing that he knew Silmeria at some point in the past, does his job as WakeUpCallBoss, and is then never seen or mentioned again.
* ''VideoGame/BaldursGate2'' had the Twisted Rune. Originally intended as the [[TheManBehindTheMan hidden cabal]] behind several sidequests, including the Athkatla slaver ring and the serial-killing tailor, the actual breadcrumb trail that was to lead to them ended up as cut content. They remained in, however, peacefully chilling in their evil clubhouse under the docks district unless the player randomly stumbled across the entrance, resulting in being dropped straight into a battle with an [[CosmopolitanCouncil eclectic]] bunch of [[BonusBoss obscenely overpowered spellcasters]] after trying to enter an ordinary-looking house.
* ''VideoGame/GoldenSunDarkDawn'' does a ([[UnreliableNarrator deliberately]]) bad job of recapping the [[VideoGame/GoldenSun first two games]] in the "Sun Saga" books and Psynergy Training Grounds in-verse. Among other things, they made Alex and [[HeroWithBadPublicity Felix]] into the {{Big Bad}}s of the story, leaving the Fire Clan, the AntiVillain main antagonists of the games, to look like "freaky dragon people from nowhere".
* ''VideoGame/GoldenSun: The Lost Age'' actually ''subverts'' this trope. At the end of the game, the main characters appear to be unhindered as they achieve their goal. Suddenly, the Wise One, a character that [[ChekhovsGunman appeared very early on in the first game but was seemingly forgotten about until the very end]], appears and summons a three-headed dragon to combat the characters. At this point, almost every playable character responds similarly to the player himself would at this point, pointing out that it's kind of odd that a being with god-like powers would do something as weird as summon a dragon to fight the protagonists, especially considering (which the characters actually point out), they've already defeated a two headed dragon in the last game. All the characters respond this way... except for token [[TheMentor Wise old master]] Kraden. [[spoiler:He realizes that nothing from a being called the Wise One could possibly be that simple, and, realizing that every major dragon they fought in the series was someone transformed, realizes that the three-headed dragon was actually the main characters' missing parents fused together. He tries to warn the characters, but is unable to before they defeat the dragon, fatally wounding their parents in the process. Whoops.]]
* ''VideoGame/BraveSoul'' has two. One is a giant flying goldfish, although it gets a pass since it's found in some sunken ruins, and most of the monsters in the game look pretty weird anyway. The other, however, is a giant beetle, found in a Dragon's cave, and can't even be fought during the first visit, because of a scripted event triggered by the associated quest taking over control and moving the player directly to the destination. The only reason it was even included was because one of the developers already made it.
* The third Darm Tower boss in ''VideoGame/{{Ys}} I and II'', Khonsclard, is some weird spinning conglomeration of rocks. Many other bosses in the series also qualify, solely acting as {{beef gate}}s or guarding {{plot coupon}}s.
* ''VideoGame/{{Drakengard}}'' is mostly a hybrid of ''VideoGame/DynastyWarriors''-style HackAndSlash and ''VideoGame/PanzerDragoon''/''VideoGame/AceCombat'' style flight combat. The TrueFinalBoss is a NintendoHard RhythmGame. It should noted that the game's soundtrack is primarily composed of classical music samples arranged to sound harsh and dissonant. All the other possible Final Bosses are fought in the same way you've been fighting for most of the game.
* ''Franchise/TheElderScrolls'':
** During the main quest of ''[[VideoGame/TheElderScrollsIIIMorrowind Morrowind]]'''s ''Bloodmoon'' expansion, the player will encounter the "Ice Giant" [[spoiler: Karstaag]]. Unlike the other participants in [[spoiler: Hircine's]] hunt, you don't get to meet him until you have to fight him in in the glacier. [[spoiler: He has a unique model: a giant, four-eyed yeti monster with horns, which is unlike anything else in the game.]] Where he came from or what he actually is never gets discussed in-game. (A popular fan theory from the time stated that he may be a Kamal, one of the [[{{Wutai}} Akaviri]] "snow demons" who staged a failed invasion of Morrowind in the distant past.) ''Skyrim'' later reveals that [[spoiler:Karstaag was a Frost Giant, an offshoot of Giants that are native to a place called The Forgotten Vale]]. How he got himself to Solstheim? Still a mystery.
** ''[[VideoGame/TheElderScrollsVSkyrim Skyrim]]'':
*** A ThievesGuild quest has [[CorruptCorporateExecutive Maven]] [[IOwnThisTown Black-Briar]] hire you to sabotage a competing meadery. The quest involves putting what amounts to rat poison into the Honningbrew Meadery's brew, and [[RatStomp killing the skeevers (giant rats)]] that prompted the owner to hire an outside exterminator. Then you find [[spoiler:an insane spell-slinging self-styled "skeever master" in the tunnels under the meadery. And he's not {{Squishy|Wizard}}, and you have no clues that he even exists until the first Firebolt collides with your head]]. After you kill him, you can loot his journal to find out his backstory, and the quest-giver admits he knew about him, and didn't inform you to avoid getting gouged for the extra "wet work", but going in you have no warning he's going to be in there and his arrival is very surprising.
*** The twin dragons Voslaarum and Naaslaarum, whom appears in the Forgotten Vale as part of the ''Dawnguard'' DLC. There is absolutely no hint that there are even dragons in that region, much less two that are ''frozen under the lake''. Unlike the Frost Giants in the area, unless you found a way around the lake you WILL meet these two during the course of the ''Dawnguard'' main quest. Fortunately, they aren't much stronger than your garden variety Revered Dragons and their only real gimmick is coming in a pair and destroying portions of the frozen lake as they dive in and out of it.
%%* ''VideoGame/{{Grandia}}''
* ''VideoGame/DragonAgeII'' has The Ancient Rock Wraith, the final boss of the first act. While there is a lore explanation for it (it's the spirit of a dwarf too evil to return to the Stone), it's only revealed after the battle.
* In the GBA adaptation of ''Literature/HarryPotterAndThePrisonerOfAzkaban'', the final boss turns out to be none other than [[spoiler:''Draco Malfoy'']]. There was absolutely no build-up to him being there whatsoever (mind you, this didn't happen in the book) and quite literally just pops up just as you're about to rescue Sirius. The battle itself has ''literally no'' impact on the story whatsoever. Its only purpose is possibly to have a more satisfying final boss as compared to the fight against Lupin (which wasn't really a fight, so much as it was "keep Buckbeak alive"). To make it worse, the game tricks you into thinking that Lupin would be the final boss, since aside from the Dementors, he's technically the last enemy Harry and his friends face in the book. Not only that, he received his own unique battle theme so you know that he's not a normal boss and he is fought at the climax of the story.
* ''VideoGame/{{Fallout 4}}'': Near the beginning of the game, the Player is tasked to help the Minutemen faction who have been held up in a building by a gang of Raiders. After grabbing a PoweredArmor and a [[GatlingGood Minigun]], the player faces against the gang of Raiders and their leader Gristle (who isn't much tougher). Partway through the fight after Gristle and most of the raiders are killed, a Deathclaw that's [[LightningBruiser much faster, stronger and tougher]] than [[TrickBoss Gristle]] pops out of the ground, serving as the ''actual'' boss of the area. The only vague foreshadowing about it is by an old woman with "psychic" visions ("Careful, kid. There's something coming. And it is... angry").
* ''VideoGame/UncommonTime'', being an RPG, naturally has lots of random monster bosses that exist only to fill the boss slot for minor dungeons. But most egregiously, ''the FinalBoss'' is one of these: [[spoiler:when the party is finally ready to perform the World Tuning for real, Alto tells them they have to destroy the magical distortion caused by their previous failed attempt first.]] There's no previous foreshadowing that this is a thing that would be necessary, even though it would have been easy to work into earlier exposition.
* Partway through TheVeryDefinitelyFinalDungeon of ''[[WebComic/{{Megamanspritecomic}} Megaman Sprite Game]]'', the comic's one-shot character [[spoiler:Iris]] shows up to become a boss battle, with an UnexplainedRecovery. Partway through the battle, she mutates into some horrorfying monster on top of her sudden appearance. This MakesJustAsMuchSenseInContext, if you're wondering how any of this correlates to the comic.
* In the [[VideoGame/PhantasyStarI first Phantasy Star]] you spend the whole game trying to reach and defeat the tyrant Lassic. Afterwards the game continues for a brief bit as you literally just have to walk a few steps to encounter the true final boss Dark Force. While the sequels expand on the presence of the Dark Force greatly, in this game it comes out of nowhere.
* Mt Nomad in ''VideoGame/SunlessSea''. It has no connection to the Dawn Machine or any of the political manoeuvring. It ''does'' have some connections to the powers of the Neath or the Zee, but they don't really play into why it attacks you, and you don't learn any of the lore while it's still alive. What you ''do'' learn about Mt Nomad while it's still alive is one, it's a self-propelled mountain; two, it can show up in the North at any time, usually but not always around the Chapel of Lights; and three, it can and will shout your ship to death without any particular difficulty and seems to take a great deal of joy in doing so.

[[folder:Shoot 'Em Ups]]
* In ''VideoGame/MetalCombatFalconsRevenge'', after defeating the "real" Anubis (who seems to be either a robot or a particularly extensive cyborg), you fought Typhon and [[AmbiguousGender his/her]] ST, Giga-Desp.
* The ''VideoGame/{{Strikers|1945}}'' series (1945, 1945II, and 1945III/1999) lives on this trope. The attract screen and the [=PS1=] version opening doesn't hint any [[spoiler:HumongousMecha forms of whatever boss fortress you face and an alien entity as the final bosses]]. Instead, the attract screens and intros show a WWII-themed shmup.
* ''VideoGame/AeroFighters'' has an alien entity -- [[KillerSpaceMonkey a giant skinless apeman]] -- break off a jar as the final boss. The second game has you fight a black eyeball that resembles Buckbaird at the end, or a BedsheetGhost, which is randomly selected. Finally, at the third game, if you proceed good, you either fought a mutant ghost submarine in Bermuda Triangle, or go off to space and fight an UFO in another route. Do badly, and you'll fight a joke cartoon thing instead. And the rest of the game is you fighting various modern-day ([[SchizoTech sometimes future]], however) war machines with a jetfighter (except the third).
* In ''VideoGame/{{Touhou}}'', the EX stage of ''Lotus Land Story'' has Reimu and Marisa wandering through a dream world, uncertain how they even got there. Cue getting randomly jumped by the ''creator of that world'' in the guise of a {{Meido}}... and, once you've trounced her, her ''[[StrongerSibling big sister]]'' shows up. It's also Lampshaded and inverted in Reimu's storyline in that game, where she only calls out and attacks the Stage 1 boss because she knows there's supposed to be a boss fight. Said boss was ''hiding from Reimu''.
* Jitterbug is built up as the BigBad of Cave shooter ''VideoGame/DeathSmiles''. After you beat him, however, [[NamesToRunAwayFromReallyFast Tyrannosatan]] suddenly jumps out of an open portal to ''eat'' him. Tyrannosatan has no relevance to the plot, and is only there to provide a more climactic final boss. [[spoiler:Although Jitterbug can come back as [[TrueFinalBoss Bloody Jitterbug]] depending on how you've done.]]
* In ''VideoGame/ALLTYNEXSecond'', after you beat the [[AntagonistTitle ALLTYNEX]] [[TheAiIsACrapShoot OS]], you are greeted with the REAL final boss, Satariel who literally has no context to it whatsoever, [[spoiler:other than it houses the Ophiuchus' core before being hijacked by ALLTYNEX.]]
* Since ''VideoGame/{{XOP}}'' has no real plot, most bosses are like this, but the final boss of the original is the most blatant. You've been fighting weird translucent aliens for the entire level, then you get the boss warning, and travel down some organic tentacled landscape, shooting blobs. Then you make it to an egg, it hatches...and a phoenix comes out and starts [[BulletHell shooting lasers all over the place]].
* ''VideoGame/GunBird2'' has you racing to collect elements to make a [[MacGuffin cure-all medicine]] to resolve whatever ExcusePlot there is in the game (each of the 5 characters has a reason for the need of the medicine) and fighting off a GoldfishPoopGang pirate crew who wants the medicine for their own evil deeds. Then you get to the main boss- [[spoiler: a giant {{Expy}} of Japanese pharmaceutical mascot Sato-chan (an orange-colored anthropomorphic elephant)]]. Ok, so maybe ItMakesSenseInContext, but it still qualifies since said final boss this was never mentioned in the game until the moment he appears, and up until then, the villain has always been said pirate gang.
* Whereas the other bosses in ''VideoGame/TwilightWing'' are powerful enemies ([[AndZoidberg and Trixie]]) from [[WesternAnimation/MyLittlePonyFriendshipIsMagic the show it's based on]], the FinalBoss is Princess Skyla, ie. a random toy-only baby character with absolutely nothing to do with the show. In her own way, she's much more creepy than the other characters that were actually designed to be intimidating.
* The enemies in the SNES game Macross: Scrambled Valkyrie are, for the most part, based on designs from the actual show, ''Anime/SuperDimensionFortressMacross'', or could at least look the part and blend in without being too jarring. As the game goes on you go through familiar setpieces from the show (and the ''Do You Remember Love?'' movie retelling) like Macross City and the rings of Jupiter, until you reach the final stage, which is set to be a recreation of the climatic scene in DYRL where Hikaru storms the [[HumanAliens Zentraedi]] command vessel. So far so good, and you even get to fight what seems to be like a slight redesign of [[BigBad Boddole]][[LargeAndInCharge -Zer]] in a similar setup as in the movie (with a giant Minmei holographic screen in the background while ''Ai Oboete Imasuka'' plays). Except he's not the final boss in this game. After you defeat him, you immediately proceed to the next room where the REAL boss resides, it's [[Film/TwoThousandOneASpaceOdyssey the Star Child]]. Then halfway through the fight it turns into a humanoid lizard alien. Yeah.
* ''VideoGame/{{Cuphead}}'' unconventionally inverts this trope with ''common enemies'' instead of bosses being out of context. All boss enemies Cuphead and Mugman fight owe their souls to the Devil, who has charged the heroes with taking their contracts back by force. The Run-and-Gun levels on the other hand, feature basic-enemies and mini-bosses who have no real bearing in the plot, they aren't in service to the Devil nor the debtors and don't offer an explanation why they want to kill our heroes so badly other than presumably [[HairTriggerTemper having set foot in their territory]].
** The third phase of the Werner Werman boss fight has him [[spoiler: being eaten by the cat that can be seen in the background, forcing you to fight the cat instead]]. But then it turns out to be a subversion as [[spoiler: when you defeat the cat, its face falls off, revealing it was a robot controled by Werner himself]].
* Many bosses in Tyrian qualify for this. Notable examples include the giant brain you fight near the end of the game, and the god Zinglon that suddenly shows up and attacks you for no explained reason after you defeat the final boss.

[[folder:Beat 'Em Ups]]
* Every other boss in ''VideoGame/GodHand'' seems to be one of these. Mind you, it's part of the game's appeal: You know that a game is unique when you get to fight two HardGay twin thugs in {{stripperiffic}} outfits, a TerribleTrio whose hobby is to cut random people's arms off, [[EverythingsBetterWithMonkeys a masked gorilla who uses pro-wrestling moves]], a rock duo from hell who attacks by shooting [[BeamOWar lazers and beams]] from their instruments, a group of five midgets dressed in PowerRangers style clothing, an afro-coifed black disco reject in a yellow vinyl suit, replete with arm tassels and flare bell bottom pants. Gene even [[LampshadeHanging comments]] this, after beating the Psychic Midget in the caverns, by saying that the paranoid old hermit seemed [[NoFourthWall to pick the wrong game to appear in]].
* Mimmy from ''VideoGame/NoMoreHeroes2DesperateStruggle''. Travis has completed one of the toughest fights in the game and is now 7th, has a tense, sort of tough-to-watch scene, and suddenly [[http://www.youtube.com/watch?v=Dfma_bqEDWY this]] happens.
* Most bosses in ''VideoGame/CharlieMurder'' that are not a member of Gore Quaffer qualifies. All of them show up without explanation, [[BigLippedAlligatorMoment and most are not commented on your phone either]]. This includes a giant sasquatch, a living brain, a hamburger/human hybrid and a bloated tumor.
* ''VideoGame/XMen'':
** The arcade game inexplicably throws Nimrod (an advanced Sentinel from the future) at you. It doesn't make any sense why he would be working for Magneto, since he was designed to hunt and kill mutants. The same could be said of {{Wendigo}}, another boss in the game who has no connection with Magneto.
** At the end of the second-to-last level, some pharaoh statues ([[http://en.wikipedia.org/wiki/Living_Monolith Living Monolith]]) attack you in the tomb without any foreshadowing, and earlier on in the level, the players get attacked by six weak clones of Pyro.
* As depicted above, ''VideoGame/{{Growl}}'' is all about beating hordes of poachers to death and freeing captive animals. When you take out their leader (a masked freak with enough strength to throw a tank), his corpse begins to slither around the arena, when suddenly [[BodyHorror a millipede bursts out of his back]] and states that ''it'' is the true leader of the poachers. (Players of the ''VideoGame/{{Darius}}'' games will recognize it as [[OutsideContextProblem one of the aliens from those games]], but there were barely any hints that ''Growl'' shared a universe with them.)
* In ''VideoGame/NoituLove 2'' we have some pretty strange bosses. Starting with [[https://www.youtube.com/watch?v=NfBQSQWYKH4&list=UU3Q13RAmFVfDkYOWnnqFM2A a boat with tank treads that tries to run you over]] in stage run, to a [[https://www.youtube.com/watch?v=f-CVtyAp8cY&list=UU3Q13RAmFVfDkYOWnnqFM2A&index=89 train that apparently thinks it's some kind of transformer]], to the last boss, which becomes [[https://www.youtube.com/watch?v=LIMWLSurr6g&list=UU3Q13RAmFVfDkYOWnnqFM2A&index=86 a fetus thing, a giant mechanical thing with gears,]] and... [[ArsonMurderandJaywalking A person.]]
* ''VideoGame/DoubleDragon'':
** Example from ''Double Dragon II: The Revenge'':
*** The arcade version took a turn to the occult for some of its enemy characters. The first boss, Burnov, is a masked wrestler who, instead of blinking into non-existence like all the other defeated enemies, will stand up and yell with his arms raised and then vanish into thin air, leaving behind his clothes and mask. In later encounters, he will rematerialize after using his death animation once. Later in the final stage, after defeating Machine Gun Willy, the game seems to be over until the player's own shadow starts gaining a life of its own and attacks the player as the actual final boss.
*** The TrueFinalBoss in the NES version is a nameless martial artist with the ability to make himself invisible in battle. [[AllThereInTheManual Unless you've read the manual]], his existence is never hinted anywhere in the game. He is also a MasterOfIllusion, which explains why your [[YourMindMakesItReal shadow gained sentience...]]
** For most of ''Double Dragon 3'', the player spent their time fighting human enemies such as bikers, martial artists, swordsmen, and scantily-clad Roman warriors. In the fifth and final stage, the enemies consist of living tree people, stonemen, and the reanimated corpse of Cleopatra (which in the NES version is a possessed Marion).
* When ''WesternAnimation/TheSimpsons'' got their own BeatEmUp [[VideoGame/TheSimpsons arcade game]] made by Konami, there was only the first season to draw material from. Thus, we got such surreal bosses as [[AdaptationalVillainy an evil Werner von Brawn]], a Krusty The Clown parade float piloted by Mr. Smithers ([[AdaptationalVillainy who is also evil]] in this game), [[ThoseTwoBadGuys two mobsters]] who copied the two-player combination attacks, a Cerny-esque fire-breathing giant hiding in Moe's Tavern, a {{bear|sAreBadNews}}, an anthropomorphic bowling ball conjured by [[BattleInTheCenterOfTheMind Homer's imagination]], and a Noh Theater actor with a BladeOnAStick. It really says a lot when the boss that makes the most sense is [[CorruptCorporateExecutive Mr. Burns]] in a robot suit.
* ''VideoGame/AnarchyReigns'' features random boss fights commencing in its multiplayer matches: particularly, a GiantSquid named Kraken, and a HumongousMecha named Cthulhu ([[DidyouJustPunchOutCthulhu which you can punch out]]).
* ''VideoGame/StreetsOfRage 3'' has each boss fit closely with TheSyndicate. The boss of stage 4 is a ninja that can [[MesACrowd split himself into three copies]], use SuperSpeed as a tackle move, [[{{Invisibility}} become invisible]], and [[TeleportSpam teleport everywhere]]. Better yet, the fight takes place in front of a Japanese styled building and the song that plays during the fight is called "Shinobi". None of the protagonists bring this up after the fight is over, though the FanRemake does lampshade at how random the encounter was.

[[folder:Fighting Games]]
* ''[[VideoGame/CombatOfGiants Battle of Giants]]: Dinosaurs'' has Mystery Bosses, who are not super dinosaurs, but instead angry inanimate objects. They include monster trucks, rockets, ''telephone boxes'', and ''a schoolhouse''. It's jarring because otherwise you're in some kind of ''Land Before Time''-esque world filled with dinosaurs, and no explanation is give for the phone boxes attacking you. On the other hand, seeing a T-Rex beat up a school is crazy awesome.
* ''[[VideoGame/BlazBlue BlazBlue]]: Chronophantasma'' and ''Centralfiction'' have [[NamesToRunAwayFromReallyFast Azrael.]] While he's not mindless, he's frequently referred to as the [[RedBaron Mad Dog]], as his existence seems to revolve solely around [[BloodKnight finding something to punch really hard.]] Even [[WordofGod the developers have stated]] that his purpose in the plot is simply being someone that anyone could fight at any given time. His origins are never explained; he just kind of shows up wherever.
* ''[[VideoGame/CapcomVsWhatever Marvel Super Heroes Versus Street Fighter]]'':
** The seventh round is Apocalypse, fair enough, he's a significant Marvel villain... and then, [[MemeticMutation Suddenly, Cyber-Akuma]]!
** Akuma similarly comes from nowhere to face you in Puzzle Fighter (then again, the boss you were "[[BaitAndSwitchBoss supposed]]" to fight is [[JokeCharacter Dan Hibiki]]).
** Akuma's first appearance as the TrueFinalBoss in ''Super StreetFighter II Turbo'', where he appears out of nowhere and kills M. Bison, who you normally fight. His name wasn't even shown then. This happens ''again'' in ''VideoGame/CapcomFightingEvolution''. The game [[NoPlotNoProblem doesn't have a plot]], yet it's still ridiculous seeing Shin Akuma suddenly showing up after defeating [[VideoGame/{{Darkstalkers}} Pyron]]. Admittedly, you can only fight him after fulfilling specific requirements, but still...
** If you said that [[VideoGame/{{Okami}} Yami]] would be the boss of ''Tatsunoko vs. Capcom'' prior to its release, everyone would be mocking you. Improved upon in ''Ultimate All-Stars'', where some characters do in fact acknowledge 1) that Yami pulled their worlds together and 2) they had to beat it to undo said pulling.
* Kaguya's boss fight in ''VideoGame/NarutoShippudenUltimateNinjaStorm4'' may qualify as this considering the asspull retcon from the original anime/manga.
* The ''VideoGame/{{Touhou}}'' fighting game ''Touhou Hisoutensoku'' features three of them.
** One is Utsuho Reiuji, the final boss of ''Subterranean Animism''. It's a bit of a stretch, though, as Sanae is descending into the geyser control center when you run into her, and if you're at all familiar with the story of ''Subterranean Animism'', you probably expect to see her or at least someone else from that game.
** After you beat Utsuho, you fight Sanae's final boss, Suwako Moriya, who actually ''does'' come out of nowhere. Given that Suwako is already in the game as one of Sanae's assists (and you can even use Sanae's Suwako assist during the fight!), it's safe to say that no one was expecting her to be Sanae's final boss.
** Even Suwako pales in comparison to the horror that is [[http://www.youtube.com/watch?v=671SA4Pg6Hw Hong Meiling's final boss in her story.]]
* Who's the final boss of ''VideoGame/GuiltyGear Isuka''? Is it Justice? Nope. Dizzy? Nope. That Man?!? Nope again. It's Leopaldon. Some strange, gigantic white beast with a huge puppy inside its mouth that is being controlled by a man in black who looks somewhat like [[Franchise/FinalFantasy the Black Mage.]]
* ''VideoGame/{{Tekken}}'':
** The final boss in ''Tag Tournament'' is Unknown: a woman whose actions are controlled like a puppet by a forest spirit -- which looks like a werewolf's torso -- floating behind her. It probably helps that the game is non-canon, but she/they still come out of nowhere.
** ''Tag Tournament 2'' has Unknown return, but is less [[BuffySpeak Space Flea-y]], because the game confirms the EpilepticTrees floating around about it being Jun Kazama. Also, as a ContinuityNod to Unknown's own ending from the first, the wolf thingie is gone.
* ''VideoGame/SamuraiShodown 6'' is a [[DreamMatchGame "festival"]] game whose [[ExcusePlot plot]] is basically that Yoshitora Tokugowa is holding a swordfighting tournament and will use his powers as "ruler of everything" to grant the winner one wish. The tournament gets [[HijackedByGanon hijacked]] by one of the four previous final bosses, ''then'' you go to HELL and fight Demon Haoh, right out of nowhere. Like the Tatsunoko vs. Capcom example above, neither the "hijacked" boss or Demon Haoh are ever mentioned again.
* ''VideoGame/SuperSmashBros Brawl''[='=]s ''Subspace Emissary'': [[Franchise/{{Pokemon}} Rayquaza]] attacking [[VideoGame/DonkeyKongCountry Diddy]] and [[VideoGame/StarFox Fox]] for no apparent reason. From a ''[[MisplacedWildlife lake]]''. It's supposed to live in the ''sky''.
** For that matter, the campagin's final boss, Tabuu. There's no foreshadowing for him, he's not a pre-established Nintendo (or other) character, he's a complete departure in art style for ''any'' other character in the game (a giant, purpley blue being with rainbow butterfly wings), and he makes his introduction by trouncing Ganondorf and Master Hand, turning the entire rest of the cast into trophies, then enveloping himself in a giant labyrinth made of the levels you've already beaten. It's strange, to say the least.
* The obscure arcade fighter/beat 'em up hybrid ''Mutant Fighter'', after having you battle a variety of fighters and beast in hand to hand/grappling combat, reveals its final boss to be...'Magician', a wizard who barrages you with spells and doesn't throw a single punch. While not as jarring as some examples, the fact that you get to the end of this elite warrior hand to hand tournament and find a magician is like getting to the end of VideoGame/StreetFighterII and finding a Franchise/{{Terminator}} expy waiting for you instead of M.Bison.
* ''VideoGame/TheKingOfFightersXIV'': You're in a straight up martial arts tournament, but when you defeat the champion, a demonic entity called Verse suddenly appears and attacks the stadium. The endings of several of the teams involve trying to figure out just what the heck Verse is and why it attacked.


[[folder:[=MMORPGs=] ]]
* ''VideoGame/WorldOfWarcraft'':
** Kil'jaeden, the FinalBoss of the first expansion, ''The Burning Crusade'', could easily be considered one of these by players who aren't well versed in the background story of the game. It's not so much that he's an unknown entity (he's not), but that all of the marketing of ''Burning Crusade'' was focused exclusively on Illidan, the final boss of the Black Temple. Kil'jaeden, despite being one of the canonical {{Big Bad}}s of the series, got almost no mention at all from the in-game story until suddenly being introduced in patch 2.4. Blizzard has actually stated themselves that they released Black Temple too early and needed to find some way to keep everyone interested in the game. Still, it worked.
** In Drak'Tharon Keep, the players fight a skeletal wind serpent named Tharon'ja. The Dungeon Journal introduced a patch and a half later explains that Tharon'ja was one of the trolls who killed and stole the power of a loa, only to be killed in turn and turned into a servant of the Scourge and the Lich King.
** Prince Malchezaar of Karazhan. The other bosses are mostly ghosts or magical constructs left behind in Medivh's castle, but while he's associated with the Eredar, it's never stated why he is there. The same applies to the nether dragon Netherspite. Malchezaar is considered by Blizzard to be the last boss of Karazhan, effectively making him its ruler, as far as the unexplained storyline goes. The question of what does the [[LegionsOfHell Burning Legion]] want to do with a place like [[EvilTowerOfOminousness that]] is left for us to wonder. [[EldritchLocation Karazhan is the only place they can do]] ''[[EldritchLocation anything with at all]]''. It reaches into the Twisting Nether and thus can be used to try and invade Azeroth. In fact, it's been hinted that Karazhan was relatively quiet up until Malchezaar appeared and started stirring up the spirits. More importantly, Karazhan is three unfinished dungeons (Well, one finished, two unfinished) combined into one.
** A lot of minor dungeon bosses are this. They get one throw-away line to explain who they are and what they're doing. Sometimes. In ''Cataclysm'' some effort has been made to explain some of the more bizarre bosses. New quests for classic dungeons offer some explanation of their background, though not every boss gets this.
** The final boss of the Worgen starting zone. Rather than using Crenshaw, the previously-introduced undead general that had bombed Gilneas City, Blizzard decided to put you and your friends up against a weird mutated orc named "The Machinist", who had never even been hinted at.
* ''VideoGame/GuildWars'' has one of these in ''Eye of the North'', the Disc of Chaos. It has some of the highest health and damage seen on a mob and uses a model that has been flipped horizontally so it floats. The Disc only appears during its fight and is never mentioned before or after. Also, whereas all other Destroyers have names in the format of "Destroyer of" or "of Destruction", the Disc is the only Destroyer to not follow this pattern.
* ''VideoGame/{{Runescape}}'':
** The game has Chaos Elemental who, instead of residing in some sort of cave or building, is located in a seemingly uninteresting and generic spot in the Wilderness.
** A few of the quests have boss battle creatures that come out of nowhere and have nothing to do with the story, just to make the quest a bit harder.
** Lampshaded in the 'could you fetch my ball from the fenced yard' quest: the unnecessary boss morphs into six or seven arbitrary forms with escalating difficulty. Inverted in that earlier in the quest, you read the witch's journal where she mentions her experiment.
** Averted in My Arm's Big Adenture. In this quest, you teach a troll how to farm. Once you have the stuff you need, My Arm (trolls are named for either the first thing they try to eat, or for the noise said thing makes; it was his father's arm) warns you about a "bird". Sure enough, once the goutweed is planted, a Giant Roc attacks you. If you're the type of player who ignores dialogue, you would have been caught by surprise. The mod who wrote the quest was probably counting on that.
* ''VideoGame/PuzzlePirates'' has "[[http://yppedia.puzzlepirates.com/Monkey_boat monkey boats]]". For [[strike:[[ForScience science]]!]] [[FakeBalance balance]].
* As silly and nonsensical as ''VideoGame/KingdomOfLoathing'' is, the final boss of the main quest takes it to a whole new level. Most other enemies in the game are parody versions of [=RPG=] monsters, which you kill with weapons and/or spells with goofy names. The Naughty Sorceress is no exception; she appears to be your basic evil female spellcaster, but her [[OneWingedAngel "true form"]] is [[spoiler:some kind of EldritchAbomination covered in eyes, fanged mouths, and CombatTentacles.]] After you beat ''that'', she takes on her "[[ExaggeratedTrope actual true form]]" and turns into [[spoiler: a goddamn ''sausage''. With ludicrously high HP and RealityWarper powers. Which can only be defeated by using ''anagrams'' to deflect its attacks.]]
* Invoked in ''VideoGame/PhantasyStarOnline2'', thanks to the randomly-generated nature of the game's stages, particularly multi-party areas, where bosses can spawn at any time. Even bosses from different fields (but still the same planet) can spawn, such as the Tranmizer, the sub-boss for Lillipa's Mines, appearing on Lillipa's Desert and Quarry. Darker bosses are exempt from the "same planet" rule, and can spawn in any field, regardless of which field they act as the boss of. Also, some event quests subvert this rule: a limited-time map introduced in February 2014 features bosses from Lillipa and Naberius spawning on Vopal's Coastline. There are only a small handful of exceptions [[spoiler:such as the Dark Falz bosses such as Elder and Loser]] due to their large size and the unique nature of their fights.
* In the ''VideoGame/StarTrekOnline'' mission "Installation 18", if you're playing as either a Federation or Klingon character, this is the first time you meet an Elachi. It's tough to fight, especially flanked by Tal Shiar soldiers, and it holds no bearing to ''either'' storylines. This is because it's actually geared towards the ''Romulan'' player, who has a whole history of dealing with these things.
* ''VideoGame/ToontownOnline'' has this as it's ''main plot'', in which robots show up from out of nowhere and started invading the game's world for just no reason.[[note]]The beta had a backstory that actually averts the trope. However, the Disney execs didn't like the story and got the writers to change it to this halfhearted ExcusePlot upon release[[/note]]
* For many players the fight against Tenzen near the end of ''[[VideoGame/FinalFantasyXI Final Fantasy XI's]] Chains of Promathia'' expansion makes no sense. Well, to be fail a lot of [=CoP's=] boss fights come out of no where, but Tenzen stands out because he has been an ally through the whole expansion (and continues to be after the fight). You've learned almost all there is to know about the expansion's plot, you've tracked down the [[BigBad Big Bad's]] location, and you're about he head off to assault the ancient hidden city of "Sea". So why your ally suddenly attacks you is beyond explanation. Some have tried to handwave it as him testing your readiness for the battles ahead, but none of the dialogue before during or after the fight backs that up.

* ''Franchise/SonicTheHedgehog'':
** The boss of the Sandopolis Zone Act 1 from the SonicTheHedgehog game ''Sonic and Knuckles''. All of the other bosses in the game (and in fact most other Sonic games) are either Robotnik or his robotic henchmen. And then at the end of Sandopolis we get this big huge... golem thingy that you have to trick into the nearby quicksand pit. It was referenced in ''VideoGame/SonicAdventure2'' with the "Egg Golem" boss. Except that one was bigger, defeated in a different way, and was a robot.
** King Boom Boo from ''VideoGame/SonicAdventure2''. Knuckles has to fight a giant bug-eyed ghost with a rainbow colored tongue for no reason. What was the point in even having this thing in? Did fighting the ghost even do anything to advance the plot?
** Also from ''VideoGame/SonicAdventure2'', the Biolizard. The only foreshadowing we get to its existence was a report Rouge found that called Shadow's identity into question. Then Sonic and company have to keep the ARK from pulling a ColonyDrop and come face-to-face with a massive red biomechanical reptile, which later fuses with the colony's WaveMotionGun to continue steering the colony towards Earth. Sure, there's some foreshadowing that Shadow is ''not'' the first constructed creature while trying to make the ultimate life form, but chances are no one expected ''this'' to be his prototype.
** The first boss of ''VideoGame/SonicRushAdventure'', the Ghost Rex. The actual plot of this game is built up very slowly, and so many of the first few levels are just Sonic and Tails trying to accomplish some things on their own, so when a gigantic, mechanical [[EverythingsBetterWithDinosaurs T-Rex]] drops down and fights Sonic before a villain has even been established, it's... jarring, to say the least.
* [[spoiler:Heinrich]] from ''VideoGame/ConkersBadFurDay''. Up until this point, the BigBad had been the Panther King. You're all ready to fight him, and [[spoiler:a xenomorph implanted by his [[TheDragon mad scientist right-hand man]] [[TheStarscream pops out of his chest]] and becomes the FinalBoss. Yes, [[Franchise/{{Alien}} THAT xenomorph]].]]
* ''Videogame/AloneInTheDarkTheNewNightmare'' features a battle with a nightmarish Insectoid Winged Demon from Nowhere MiniBoss in the Library. There's also some sort of sea monster that attacks you in the sewer (if you play as Edward) or out of a ''rug'' (if you play as Aline).
* ''VideoGame/{{Postal}} 2'' was a semi-realistic game in that there were no "bosses" or monsters, just a free-roaming journey through a town inhabited by assorted screwed-up gun-toting humans with varying levels of craziness. ''Postal 2: Apocalypse Weekend'' ends with the sudden and completely out-of-left-field appearance of a "final boss" in the form of a 20-foot tall demonic half-cow half-man who declares "I am Mike J, Kosher Zombie Mad Cow, God of Hellfire! All bow down, and worship my asscock!" and summons severed and floating heads of Gary Coleman to create a bull-proof shield around him. The Postal Dude promptly lampshades the trope by stating "Some designer has lost his tiny mind". The only thing you get as forewarning is somebody saying that Mike J, the game's Producer, had to call in sick. At first you think this is just from The Dude's head wound as the other hallucinations were... until Mike J returns in ''Paradise Lost'' still mutated and massive. The DLC has weirder parts as well.
* While every boss starting with Kling Klong in ''VideoGame/LittleBigPlanet 2'' is some creature either created by the Negativitron, the boss of [[EternalEngine The Factory of a Better Tomorrow]] is... Copernicus the Guard Turkey. No one ever mentions that the factory even '''has''' a Guard Turkey, but when you beat the fourth level of the world, Clive will show up, horrified, and tell you that Copernicus is on the loose. After a [[AdvancingBossOfDoom quick chase]], Copernicus is dead and the plot resumes as usual.
* ''Win Back'': Jin, the McNinja boss, is a blatant example. He is the only boss in the game to not have any introductory dialogue before the battle.
* The final boss of ''VideoGame/RazingStorm'' is an enormous skull-shaped battleship. One of your comrades lampshades its sudden appearance by asking why no one told him about it, to which someone else responds, "Because we didn't know about it! Now [[MoreDakka keep firing]]!"
* "Caduceus", the final boss of ''VideoGame/{{Strider}} 2'', not only pops out of nowhere with no explanation or relevance to the plot, but is in fact gigantic, fought in outer space, and unmistakably flea-like.
* ''VideoGame/BeyondTheBeyond'' has Akkadias as the final boss, who is not mentioned anywhere prior in the entire game. The rest are all plot-relevant.
* Spider-Man is a [[http://www.i-mockery.com/shorts/shinobi-vs-spiderman/ boss fight]] in ''Revenge of VideoGame/{{Shinobi}}''. The only foreshadowing of this is a "Copyright of Marvel Comics" at the beginning of the game. Franchise/{{Batman}}, Franchise/{{Godzilla}}, and a Franchise/{{Terminator}} were also bosses in some versions of the game. Seems like Sega liked NoCelebritiesWereHarmed.
* The [[MultiArmedAndDangerous six-armed]] humanoid ("God Vishnu" according to the sound test) in Level 17 of the SNES AdaptationExpansion of ''VideoGame/PrinceOfPersia1'' has no relevance thematically to the rest of the game. It is the only boss other than the FinalBoss with a unique BattleThemeMusic, the only enemy that doesn't appear in the manual, and the only one that doesn't swordfight you.
* Most bosses from ''VideoGame/BlueDragon'' don't really tie into even the countless sub-plots, and no one bats an eyelash after slaying them.
* A Sachen game called ''Silent Assault'' had numerous bosses which even didn't make any sense. This is supposedly a game where aliens and mind-controlled humans are attacking the Earth, but bosses also consist of a floating skull, a computer with a mouth, a clown's head on a boot, a fire-breathing tree, and, as a final boss, a pair of sphinxes. However, it's Sachen so what do you expect.
* ''VideoGame/DonkeyKongJungleBeat'' features our simian hero fighting warthogs, other gorillas, and the occasional robot elephant. Then you get to the final boss fight, and meet: The Cactus King, a weird, green, giant space-gremlin with what looks like a dead tree for a head and rides a fire-breathing pig. Nothing in the game even hinted toward this character's existence, he has no motives, and totally clashes with the aesthetic featured in the rest of the game.
* The Kalhar Boss Monster in ''VideoGame/SuperStarWars'', which only briefly appeared in the film as a holographic chess piece, randomly appears out of the blue to block you from meeting Han Solo in the Cantina.
* The almost forgotten SNK side shooter ''[[VideoGame/PrehistoricIsle Prehistoric Isle in 1930]]'' has the some of the usual StockDinosaurs as boss encounters, except the fourth one which is appropriately named "Unknown dinosaur": Part plant and part whale.
* The ending to ''VideoGame/{{Borderlands}}''. You're all geared up to fight Commandant Steele, whose mercenaries have been making your life difficult for the last quarter of the game, when suddenly [[spoiler:a massive EldritchAbomination pops out of the vault, impales Steele and swallows her whole, and then tries to kill the player.]]
** Crawmerax the Invincible, which you can fight after finishing the main story of the DLC ''The Secret Armory of General Knoxx'', is an honest-to-goodness Giant Space Crab from Nowhere. The only background for the quest is that there is a legend about a giant invincible crab and that there have been tremors since you completed the final story mission. It has no bearing on the main story at all.
* The ending to Borderlands is lampshaded in the intro of ''VideoGame/{{Borderlands 2}}'', where Marcus states that the only things the Vault Hunters found were tentacles and disappointment. Also from ''2'', the giant loader Saturn shows up with absolutely no warning at all. Subverted however with The Warrior, which is frequently discussed in-game as a superweapon of great power.
** ''2'' sees the return of Invincible Space Fleas from Nowhere, including the Giant Space Tentacle Monster from Nowhere named Terramorphous the Invincible, the Regular Sized Space Engineer from Nowhere named Hyperius the Invincible, and the Larger than Average Space Kung Fu Master from Nowhere named Master Gee the Invincible, among others.
* ''VideoGame/BorderlandsThePreSequel'': The Vault on Elpis is guarded by the Sentinel, a giant Eridian robot that vaguely resembles the Guardians. It's not foreshadowed at all beforehand (in fact, an entirely different character is foreshadowed as the final boss, but she turns out to be something entirely different), and no one talks about it afterwards.
* ''VideoGame/TalesFromTheBorderlands'': When people discuss the Vault of the Traveler, no one mentions that the Traveler is a giant indestructible teleporting golem-thing, so it comes as a surprise when it shows up at the end of the first act of episode 5. Though if you played any other game in the series, you probably saw it coming. Atlas certainly did; [[spoiler:the same upgrade that lets Gortys summon the Vault also turns her into a giant robot big enough to fight the Traveler. Too bad Atlas didn't have time to give her combat programming]].
* In ''VideoGame/{{Fable|I}}'', escaping a prison with your mother ends in a battle with a Kraken. What it's doing there or how it survives in what appears to be a pond of water just large enough to contain it is anyone's guess.
* ''VideoGame/SigmaStarSaga'' gives us a few of these, including some ''literal'' giant space fleas from nowhere.
* Indy platformer ''WilliamAndSly'' has this with its final and only boss. Okay, it is mentioned in the beginning that something strange must be going on at the storehouse. But still...the game is an hour or so of relaxing platforming in the vein of ''VideoGame/{{Knytt}}''. Impressive vistas, all exploration and scavenger-hunting, only a handful of not-very-threatening enemies. Then you top it off with an awkward and difficult fight against [[spoiler:a giant phantom in the shape of a cobra's head]].
* ''VideoGame/SuperMarioGalaxy'':
** Baron Brrr has no lead in from the level to the boss other than being there, and unlike nearly every other boss, never appears again.
** The Undergrunt Gunner, the very common cannon Monty Mole, doesn't even get mentioned in the mission name, and appears in two levels completely out of the blue (and one, he's just guarding the cannon, right at the start of the level, and you don't even need to use said cannon).
** Kingfin is [[DemBones a giant skeletal fish]] living on his own water planet. It's the only boss located on a single-level galaxy, and the only reason you fight it, aside from the star it keeps, is because you've just entered its territory.
* In ''VideoGame/SuperMarioOdyssey'', after leaving the [[LevelAte Luncheon]] [[CloudCuckooland Kingdom]], Bowser sics a previously unseen enemy, [[spoiler:the Lord of Lightning]], on Mario. Said enemy is [[spoiler:a massive [[NonstandardCharacterDesign photo-realistic]] dragon who looks like he flew in from ''VideoGame/TheElderScrollsVSkyrim'' and is fought in grim, crumbling arena that would fit comfortably in ''VideoGame/DarkSoulsIII'']]. No explanation is offered for where he came from or what he is.
* The FinalBoss in ''VideoGame/{{Doom}} 64'' is a giant space fly from nowhere, and a {{Subversion}}. It is alluded to only [[AllThereInTheManual in the manual]] as what's been reviving and mutating the Demons for another invasion. The whole game and the collection of the three items for the superweapon are basically to stop this demon's resurrections from continuing.
* In the game ''VideoGame/{{Sanitarium}}'', after navigating a hedge maze, you have to face a scarecrow with a pumpkin for a head, wielding a scythe. The game may be based in [[spoiler:the PC's subconscious mind]], but this was a serious LevelBreaker.
* Tutankhamenattack in the NES version of ''VideoGame/LifeForce'', which is, as his name suggests, a giant pharaoh mask. The stage is also a BigLippedAlligatorMoment. The international releases of the game using the "fight through an evil invading alien fleet" graphics from Salamander while putting the "fight through the body of a giant planet-eating alien" plot from the arcade version of Life Force (an UpdatedRerelease of the ''Salamander'' arcade game with redone graphics to match the plot change) in the manual didn't exactly help matters.
* In ''[[VideoGame/DawnOfWar Dawn of War: Winter Assault]]'', there are two campaigns, Order (Imperial Guard and Eldar) and Disorder (Orks and Chaos). If you play the Disorder campaign before you play the order campaign you will be immensely surprised in mission five when [[spoiler:Necrons, whom you had no knowledge of even being in this system, let alone coming to this planet, land and attack you. When you play the Order campaign it is explained by the Eldar characters that the Necrons are coming and why they want to attack.]] But if you play Disorder without playing Order first they seem like a Giant Space Flea From Nowhere.
* After defeating the BigBad Plutonium Boss of ''VideoGame/BlasterMaster'', a strange cyborg knight with a [[WhipItGood plasma whip]] appears out of nowhere to challenge you.
* In ''VideoGame/LegendaryWings'', after defeating the last version of the RecurringBoss, you fight a teleporting robotic GiantEyeOfDoom for the TrueFinalBoss.
* Magic Mushroom from ''VideoGame/TonicTrouble'' who randomly shows up to [[ItMakesSenseInContext steal your last piggy bank.]]
* The appropriately-named Unknown Entity in ''VideoGame/TombRaiderLegend''.
* This is always what forgotten beast attacks in ''VideoGame/DwarfFortress'' are. They attack with no warning, kill everything they find, and then promptly are killed or the fortress is wiped out.
* In ''VideoGame/MasterOfOrion'' a Giant Space ''Amoeba'' From Nowhere will occasionally show up and charge across the map, killing everything in its path until it's destroyed. If you take it down, you get a significant boost to your standing with the other races. In the sequel, it's a mild nuisance at best, unless you happen to encounter it at the start of the game, and it eats one of your planets, leaving behind a toxic rock that takes a very convoluted method to turn back into a habitable planet.
* ''VideoGame/PuyoPuyo Fever'' has an interesting case. It isn't the boss of the game that makes sense (no, it's just a big plot hole), but the ''secret boss''; Carbuncle, who awards you for finding him with '''the hardest fight in the game series'''.
* The final stage of the story mode of ''VideoGame/FZero GX''. Most of the story involves Captain Falcon taking on Black Shadow and Deathborn, both of whom are introduced in the first cutscene. Nothing vastly out of the ordinary until the final stage, where, just as the story is being wrapped up, [[spoiler:three ghosts representing the developers appear and announce that Deathborn was wrong about everything. They then challenge Captain Falcon to a race in a kind of digital dimension. He defeats them, they vanish, and the story just ends there.]]
* ''VideoGame/TheHouseOfTheDeadOverkill'' has the Crawler boss, that is almost this trope word for word. It is a giant mutated preying mantis ([[BodyHorror that may have been]] [[WasOnceAMan once a man]]) without context that attacks the train G and Washington are riding in.
* The final boss of ''VideoGame/TokyoXtremeRacer 3'' is a [[MirrorBoss ghost copy of your own car]].
* Monstrous in ''VideoGame/RidgeRacer 6'' and 7 has no maker stated, making this machine even more mysterious. Racers have to wonder if where did this machine come from. [[spoiler: Even Kamata Angelus and Soldat Crinale users don't know about it.]]
* In ''VideoGame/DanceCentral 2'', the entire career mode seems to hint that the Glitterati are the final boss. However, once you beat them, you're suddenly picked up by a passing airship, which reveals a mad scientist who wants to use his robots to replace all the dance crews in the city. Suddenly you have to do five dances in a row with hardly a break in between to beat them. And you have to get near-perfect scores for each one, or you lose. This boss is never even hinted at throughout the entire game until he suddenly appears to kidnap you.
* In ''VisualNovel/HatofulBoyfriend'', dating [[CloudCuckooLander Anghel]] somehow ends in a [[GenreShift turn-based JRPG battle]] against an EldritchAbomination summoned by the school doctor with dark magics. [[http://lexlee20.tumblr.com/post/23616979639/omg-himnesia Fan theories]] posit that this creature is actually Anghel's SuperpoweredEvilSide [[spoiler:and a representation of the plague the doctor implanted in Anghel]], but during a first playthrough it's pretty confusing.
* ''KingdomRush'': There you are, fending off bandits, orcs and other such enemies from attacking your castle, placing your newly acquired paladins and wizards here and there. Cue [[MookMaker drone-shooting]] HumongousMecha who beats the everloving crap out of your troops. The other two bosses aren't nearly as unexpected.
* In ''VideoGame/ArmoredCore'', it seems the most notable difference between Normal and Hard Mode is that Hard will occasionally throw an extra enemy AC/NEXT at you, regardless of your actual mission objectives. While they aren't exactly "Giant Space Fleas" (you face other AC's/NEXT's all the time in regular gameplay), you can't help but notice that their timing is impeccable, especially if you just finished your main objective and [[ThisIsGonnaSuck you're running on low health and/or ammo.]]
* ''CybermageDarklightAwakening''. You've fought your way through all manner of gun-toting {{mooks}}, [[MechaMook killer robots]] and genetically-engineered SuperSoldiers in high-tech research labs, a crime-infested WretchedHive, the headquarters of a Megacorporation, a blasted-out battlefield, and an AbsurdlySpaciousSewer (twice) - all bread-and-butter for a FirstPersonShooter in the CyberPunk genre. Then right before TheVeryDefinitelyFinalDungeon you find yourself inside a gothic citadel with unmistakably medieval architecture, fighting off robed cultists and [[LivingShadow LivingShadows]] that wouldn't look horribly out of place in Creator/OriginSystems Inc's other game, ''{{VideoGame/Ultima}}''. Even AllThereInTheManual sheds no light on the in-universe origins or plot significance of this place.
* Golden Freddy in ''VideoGame/FiveNightsAtFreddys'' is very different from the four animatronics who try to kill you - he's an empty and discolored Freddy costume who only appears when "summoned" and can only disappear when "unsummoning" him (i.e. changing camera views). Nothing foreshadows him, he is never explained, and if he kills you, the game ''outright crashes''.
* The ''VideoGame/FiveNightsAtFreddys'' fan game ''VideoGame/FiveNightsAtFuckboys'' has the sudden inclusion of Vile from ''VideoGame/MegaManX''. Although he's [[AdaptationPersonalityChange a whole lot more vulgar,]] and has a vendetta against his father; [[spoiler: Toy Freddy, who he mistakes for normal Freddy.]]
* ''VideoGame/{{Pikmin}} 2'': There's the Waterwraith; it appears in only one dungeon, and it's never really explained where it comes from (the ship says it might have come from another dimension).
* ''VideoGame/YuGiOhReshefOfDestruction'' has the Chevaliers. In their introduction, they simply say that Master Chevalsky turned them into what they are. That's all you get from them, and that makes them even more creepy.
* The FinalBoss of ''VideoGame/YoshisNewIsland'' is Bowser. No, not Baby Bowser, we're talking about the ''adult'' Koopa king himself. When you defeat Baby Bowser, it seems as if you've beaten the game, but then Bowser abruptly appears, and you're forced into a BossOnlyLevel, complete with [[OneWingedAngel a giant phase]] (minus the GlowingEyesOfDoom like the giant Baby Bowser had). When you defeat him, he disappears and is never mentioned again.
* Most of the boss fights in the ''VideoGame/DeadRising'' series are unconnected to the main plot, and are simply regular people who FreakOut over the surrounding zombie outbreak. Larry from the first game is probably the best example of this, a random butcher who just so happens to be the one who [[spoiler: kills the BigBad]]. Some bosses such as the Convicts also have no warning before they show up.
* The monsters of ''VideoGame/{{Evolve}}'' are treated as such in-universe. No one knows where they're from, why they're here, or what they want. A few specific conversations gives the player a basic understanding of the answers. [[spoiler: They're from another dimension, they were drawn here by the Patterson Effect, and they want to bring the universe into a more stable state. The destruction and slaughter were merely in pursuit of that goal, though their success will mean no one is left to care.]]
* Game adaptations of ''Film/{{Casper}}'' give Carrigan this treatment, having her not show up until near the end as the final boss, already a ghost.
* The undead missions in ''VideoGame/WarcraftIII: The Frozen Throne'' have [[VillainProtagonist Arthas]] go through the ancient [[SpiderPeople Nerubian]] city of Azjol'Nerub. Most enemies he fights there make sense - Nerubians, people with a grudge against him, local wildlife - until he meets the [[{{Cthulhumanoid}} Faceless Ones]], strange and unintelligible monsters never seen or hinted at before, though at least they are handwaved as creatures locked up there a long time ago. Which is more than can be said about their boss the "Forgotten One", a gigantic mass of flesh, eyes and teeth that sprouts barbed tentacles everywhere, doesn't move, and isn't even a hero unit like other bosses. It's immediately forgotten after its death and isn't brought up again. ''World of Warcraft'' would later show that it probably had ''something'' to do with [[EldritchAbomination Yogg-Saron]], but what it actually was is never properly explained.
* Golden-Eye from ''[[VideoGame/{{Turok}} Turok 2: Seeds of Evil]]'', whom you face at the end of the fourth level, the Lair of the Blind Ones. The blind-ones are a race of sightless cave-dwellers, and once they're dealt with, you find yourself in a large empty chamber for the strangest boss battle in the game: a large orangish eye in the ceiling that glares at you while fighting you with tentacles and a swarm of maggots. What Golden-Eye is supposed to be (besides disgusting) is never explained; one could conjecture that it's the leader of the Blind Ones, and the maggots you fight could be them in larval form, but no concrete information is given.