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[[caption-width:320:...I thought this game was about POACHERS, not ''giant space worms''! ]]

->"Look, what gives you the right to just waltz into our show and declare yourself the new villain? Everybody's been expecting me to duel Marik, not his imaginary childhood buddy Melvin!"
-->--'''YugiohTheAbridgedSeries'''

We expect bosses, situational if not logical. They're going to be there [[SuspiciousVideoGameGenerosity after a save point]] ([[NintendoHard you hope]]), at the end of the dungeon, or the [[ClimaxBoss climax of the story]]. You may hate the QuirkyMinibossSquad or the GoldfishPoopGang, but it makes sense you'll fight them, and then TheDragon later. Then maybe ''his'' boss, who might go all [[OneWingedAngel mutatey]] on you.

But bosses don't always mesh well with the storyline, with some functioning more as checks to make sure the party is leveled up properly to this point. And sometimes it feels like a game just wanted to give you something big to fight at the end of a plot thread for dramatic effect.

This is a GiantSpaceFleaFromNowhere: A boss with no relevance whatsoever to the actual plot. 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. Don't expect any of the characters to actually comment on these bosses after you've finished them off; they exist only to give you something to pummel at the end of a dungeon. They are sort of the opposite of the BossInMookClothing: wheras the BIMC is a creature as hard as a boss which appears as a random encounter, the GiantSpaceFleaFromNowhere is a random encounter that happens to play the role of a boss. May also serve as a TrueFinalBoss.

Compare the non-video game equivalent, the BigLippedAlligatorMoment. In fact, if, in addition to coming out of nowhere, having little or no relevance to the story, and little or no mention of afterward, the boss and/or the battle is really weird and nonsensical even in the context of the game, there may be some overlap between GiantSpaceFleaFromNowhere and BigLippedAlligatorMoment.

----
!!Examples:
* In Spiderman vs the King Pin Spiderman fights a gorilla as a miniboss while in Central Park looking for Sandman. Seriously, a gorilla.
* The ''FinalFantasy'' series has a bunch of them.
** ''FinalFantasyIV'' contains a prototype for these types of enemies in Zeromus, its final boss. He had only a vague connection to the plot, as 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.]]
*** Though to be fair, you ''do'' come in at the tail end of Fusoya [[spoiler: and Golbez]]'s showdown with Zemus, and the guy takes a Double Meteor spell before going down. So maybe if you had gotten there a little earlier...
** ''FinalFantasyVI'' had Dullahan, a monster based on CelticMythology, appear for no reason in Darill's Tomb. No explanation, no build up, it just appears. To be fair, though, a lot of the ordinary monsters didn't make a whole lot of sense either -- I mean, pierrot clowns inside a giant landworm's stomach?
*** In the final dungeon, Inferno, a palette swap of a previous boss, jumps down on one of the groups with no explanation for who he is or even any dialogue about him.
*** There's also Ultros, the most amusing Space Flea ever. He's a giant purple octopus who comes out of nowhere and decides to fight you. When you give him a beating, he escapes and later comes back to wreck the opera you're attending, among with other situations. No one knows why he hates the player characters so much.
*** Then there's Doom Gaze, who shows up in the World of Ruin as a literal random encounter while you're flying around in the airship.
** A few bosses were added to the English language localisation of ''FinalFantasyVII'' (and eventually carried over to the Japanese version as ''Final Fantasy VII International''). Schizo, a two-headed dragon which appears for no obvious reason, was one of these. There's no dialogue given before the characters encounter the boss, just a bizarre polygon sequence; and the boss is ThatOneBoss and encountered shortly before the player reaches a different, plot-based RecurringBoss.
*** Schizo is probably supposed to be a reference to the penultimate boss of FFIII, the two-headed dragon. Although why they would add such a reference to the version of the game meant for audiences that wouldn't even see a proper localization of said game in their country for another ten years is a total mystery.
*** There's also the Materia Keeper, who's just standing there, guarding the exit of Mount Nibel because... umm... someone has to?
*** Interesting in that both Schizo and the Materia Keeper are ThatOneBoss for most people. Apparently in FFVII, bosses are weaker if they actually have something to do with the story.
** ''{{Final Fantasy VIII}}'' has Abadon, who just appears out of nowhere as the party walks towards Esthar.
** A similar example is Necron (''[[{{Warhammer 40000}} nooo]]'') in ''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. One is left wondering if the designers wouldn't have been better off making Kuja a SequentialBoss.
***The webcomic ''[=~Adventurers!~=]'' directly referenced Necron with [[http://www.adventurers-comic.com/d/20060103.html Necrevil]]
*** WordOfGod says that Necron was a "thematic" final boss, acting to fight Zidane's desire to live with a being who represented total death (as opposed to Kuja, who was pretty much just deluded). The writers never even tried to tie him into the plot, though, stating he "could have" been several things.
**** The tree of life which was the crux of the plot exploded after his death. That's part of why it's a major issue. He has a very major plot role, and is important to the storyline. Just... we don't know how.
*** In the Japanese version, Necron's name (when translated directly into English) is "The Eternal Darkness". This is a pretty clear indication that he isn't meant to be a character at all, but just a thematic battle against a force of nature.
** During the first three chapters of ''{{Final Fantasy X-2}}'', you can go to Bikanel Island and salvage machina parts on scouting trips. On occasion, your companion robot will flash red and warn you of an incoming enemy, at which point the 333,444-HP boss Angra Mainyu will home in on you and strike. Though, it's not until Chapter 5 that you get to (properly) defeat him.
** While we can't very well say that ''all'' the [[BonusBoss Notorious Monsters]] in ''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.
* Dark Force, the final boss of ''PhantasyStar'', was initially one of these, but was {{retcon}}ned into having an expanded role in the ''PhantasyStar'' mythos in later games. You can say that he "graduated" from Space Flea status.
** Although this is still very much the case with "Dark Falz" in ''Phantasy Star Online''. Granted, pretty much every boss was a Giant Space Flea, because the plot was entirely optional.
* ''DragonQuestII'' had one of the earliest examples of the Giant Space Flea from Nowhere final boss. After defeating the BigBad of the game, Sidoh (Malroth in the US 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 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.
** ''DragonQuest'' in general is ''terrible'' about doing this to the ''final boss of the game''. Even the very first one, the original text had the Dragonlord's pet superdragon come out of nowhere after you beat him (although the first translation [[{{Woolseyism}} changed this to his "true form"]] to help make the fight climactic and continuous.)
**''[[DragonQuestIII DQIII]]'' drops Zoma on you in a NotSoFastBucko that, admittedly, turns pretty awesome but isn't foreshadowed even a tiny bit. Unless you visit an easily-missable cave with a hole that leads to the "Dark World," and even then only if you remember the LawofConservationofDetail.
**''[[DragonQuestV DQV]]'' has Grandmaster Nimzo (Mildrath in Japan), whose world is a dull ScrappyLevel and who takes away from the satisfaction of defeating the really hateable earlier villains (although at least the game hints at his existence before insisting that he has to die right now).
*** The fact that the previous BigBad was the High Priest of the ReligionOfEvil might have explained it somewhat. Also, there is the fact that it's made cool when you consider that you're basically ''[[ToHellAndBack invading Hell]], [[DidYouJustPunchOutCthulhu killing Satan]]'', and getting revenge on the being who orchestrated every horrible thing that happened to your family the whole time.
**Deathtamoor of ''[[DragonQuestVI DQVI]]'' gets namedropped pretty late in the game, as well, with his evil being pretty much OffstageVillainy, via his minions.
**The only games which really avoid this are ''[[DragonQuestIV IV]]'' ''[[DragonQuestVII VII]]'' and ''[[DragonQuestVIII VIII]]'', who have villains who get some build up well in advance (''[[DragonQuestVIII DQVIII]]'' is particularly good about it, having him dog your steps from the very start of the game, even if you don't know it at first.)
***Not that Dragon Quest VIII is without them, though. Megalodon and Ruin (from when you're trying to escape [[spoiler:The Black Citadel]] both fit this trope pretty well.
***And VII is not without its Giant Space Fleas From Nowhere (although you're generally dealing with the effects of said Space Fleas); it's just that the (plot relevant) final boss is set up from the very beginning of the game. There are two BonusDungeons, with [[BonusBoss Bonus Bosses]], but they're, well, bonus dungeons.
* In ''{{SaGa}} Frontier'', one of the characters has as a final boss a gigantic actual Mecha Shiva that drops down from the roof of the church where she's pretending to have a wedding ceremony with the party in lieu of her dead boyfriend [[spoiler:(who's actually the antagonist, although what relation he has to do with said multi-armed robot is unknown)]].
** 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 Emelia's arc.
* In ''MetalCombat'', after defeating the "real" Anubis (who seems to be either a robot or a particularly extensive cyborg), you fought Typhon and his/her ST, Giga-Desp.
* ''BreathOfFire III'' was ''really'' bad: It would require you to battle dozens of non-plot-related bosses at seemingly random intervals. An example would be when you go to the beach to look for machine parts and are attacked by a giant fish. The game goes further by [[BossRush making you fight every one of these mini-bosses]] just before the final boss (making the whole thing seem like {{Filler}}).
** I wonder where the hell the giant chicken in the [=McNeil=] chicken coop came from.
** To be fair, the previous BreathOfFire games were just as bad. Probably worse, actually.
* Discussed in the elaborate StrategyGuide for the remakes of both ''{{Lunar}}'' games. Designer company Working Designs chose to remove several [[GiantSpaceFleaFromNoWhere Giant Space Fleas]] for just not making sense with the storyline. Of course, the remakes put a lot more emphasis on some of the badies that ''did'' make sense.
* ''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.
* The video game ''TheMatrix: Path of Neo'' 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 Wachowski Brothers [[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 ''DevilMayCry 2''. He pops out of the carcass of the previous boss without any prior in-plot mention of his existence. On the other hand, given the quality of ''Devil May Cry 2'''s plot, that's not very different from anything else in the game. It's unfortunate, too, since he's probably the best thing the game has for boss fights.
* ''Super 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.
* ''Immediately'' after defeating the [[SequentialBoss first]] final boss of ''{{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.
* "''Genji II'' 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 AncientJapan. [[http://www.destructoid.com/behold-the-most-hater-ps3-video-possible-27094.phtml So here's]] this GiantEnemyCrab..."
* ''MetalSlug 3'''s first four and a half levels are a fight against a human army... until you defeat the commander. At that point, an alien springs from his body, and the last half of the last level is a war against the invading aliens known as the Mars People. The series takes RefugeInAudacity, though, so most players's reactions are "Oh, ''cool''!"
** The Mars People appeared first in Metal Slug 2, with small, ''small'' clues in the game before they showed up, so their appearance in part 3 isn't entirely unexpected. No, the real kicker was in Metal Slug 6, when ''different'' aliens show up out of nowhere and start ''eating'' the Mars People.
** Sol Dae Rokker, the boss of mission four, supposely "an artifact of the solar deity that some Japanese believe in". But again, some 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 the WorldWarII ended decades ago.
*** Everybody calls it "Sol Dae Rokker" in English. However, "Sol de Roca" seems a more accurate transcription for the katakana in the original design sheets. Which makes sense since, well, it looks like a sun and it's made of rock. And the artifact design looks a lot like a mayan god IMHO, which would explain the Spanish in the name.
** The Final Boss of Metal Slug 5 is another example of this trope. After fighting a terrorist cell for the whole game, your last opponent is... a giant demon.
* ''CaveStory'' is solid for most of it (even the fight against a tiny superfast mushroom makes sense). Monster X and the giant fish, 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, the giant fish is apparently pulled directly out of one of the creator's earlier games. There's also the thing that 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 final final FINAL final boss chamber.
* ''WildArms 5'' lives and breathes this one. At least once a dungeon, the characters will walk into a room, exclaim, "something's coming!" and enter combat with a giant evil spider or the like that is literally shown ''appearing out of thin air''.
** The third game was even worse about this. At least ''[=WA5=]'' provided minor introductory scenes, as noted above; frequently, in ''[=WA3=]'', you'd be hit with the battle transition and the boss theme ''as soon as you walk into the room.'' The party defeats this monster in combat, then move on through the dungeon with absolutely no comment from anyone.
* Every other boss in ''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}} ourfits, 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 intruments, 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]].
* Parodied in ''{{Adventurers}}!'' -- possibly even a direct parody of Necron -- when, after finally defeating the distinctly non-Space-Flea FinalBoss and fleeing his collapsing lair, the party is suddenly faced with [[http://www.adventurers-comic.com/d/20060103.html Necrevil]], "the embodiment of evil ''itself''!"... and they just keep running.
** [[http://www.adventurers-comic.com/d/0170.html Eternion on his first appearance]] is also an abrupt GiantSpaceFleaFromNowhere, but he becomes a recurring villain and arguably has more of an impact on the plot than the BigBad himself.
** While he's decidedly more human than most examples of this trope, [[http://www.adventurers-comic.com/d/0295.html this guy]] still qualifies by dint of location.
* Could be argued for the Grotesqueries in ''{{Drakengard}}''. The characters cannot easily explain where they come from, or why they are [[spoiler:devouring everyone]]. They just know that the moment they killed the BigBad, all hell broke loose. This is definitely the case with the [[UltimateEvil Queen Mother of the Grotesqueries]] however. She literally comes out of nowhere, and [[HandWave for some reason]] controls space and time. Some EpilepticTrees try to explain where she came from, anthoug the sequel explains they're [[spoiler: supposed to be gods]].
* ''{{Xenogears}}'' had a bunch of these. Often, dungeons would just have an obligatory battle at the end because tradition says you need one.
* A few times in ''SuperSmashBros Brawl'''s ''Subspace Emissary''. Most of the bosses only make sense in retrospect. Aside from being evil, there's usually no real explanation. Case in point: [[{{Pokemon}} Rayquaza]] attacking [[DonkeyKongCountry Diddy]] and [[StarFox Fox]].
* Parodied in ''[[HomestarRunner Stinkoman 20X6]]''. The boss of the [[UnexpectedGenreChange Gradius-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." (It's actually a robot gangster.)
* The ending of ''NoMoreHeroes'' has '''got''' to be a parody of this, with a long stream of nonsensical boss fights and totally non-foreshadowed plot twists which push Travis to break the FourthWall and complain that the developers are just making this up as they go along.
*''True Crime: Streets of L.A.'' has pretty much a whole chapter called House of Wu made of this trope. The boss of the chapter is [[spoiler:''a huge Chinese dragon that breathes fire and swims around a lava pit'']]. Since the game is pretty much 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 admited this level was pretty much TheArtifact of a prior build and apologized.
*''MarioAndLuigiSuperstarSaga'' had Trunkle, a rock-creature who suddenly appears at the end of the desert section to menace the princess for a distinctly nonspecific reason.
** The Commander Shroob from Partners In Time is a noteworthy one, especially since he's the only Shroob you encounter on Star Hill. The Elder Shrooboid is a mixture of this and DiabolusExMachina, since before he fights you, [[spoiler:he turns Kylie and Toadbert into mushrooms to prevent them from telling you the truth about the Cobalt Star]].
** MarioAndLuigiBowsersInsideStory has oddly, Bowser himself at two points. For one, he appears at Dr Toadley's Clinic out of absolute nowhere to fight Mario and Luigi with the special attacks he's learnt so far through the adventure, despite the fact you were just controlling him about two minutes ago and he was at the bottom of the sewers knocked out by a rogue security system the last time around. There's also Bowser X in the Gauntlet... which is inside Bowser's own body, Chakron on some mountain area (he's not quite non relevant, he's responsible for the Chakroads Bowser uses to travel around and the ending message) who needs to be knocked over by Luigi's Snack Basket move (another trip to the other side of the map awaits), and some of the giant bosses (Giant Princess Peach's Castle? Tower of Yikk?)
* On the whole, ''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. What's worse is that this is [[ThatOneBoss one of the hardest boss fights in the game]]. And given the absurd nature of the boss in question, this might be one of the times where this trope overlaps with BigLippedAlligatorMoment.
** Punchinello from earlier in the game qualifies too. He has no lead-up, no one says anything about him, he's not one of the BigBad's lackeys, and seems to have no reason to exist other than to make you fight someone for the third Star Piece. Punchinello badly wanted to be a feared supervillain, but nobody in the party knew who he was, and their asking him "who?" angers him so much that he attacks. His whole gag in the storyline is that he came from nowhere.
** Boomer has little connection to the plot or role besides serving as a boss to fight before Exor. Similarly, the Czar Dragon's role isn't fully explained, either.
* Smorg from ''PaperMario: The Thousand Year Door''. While its individual components do cameo here and there throughout Chapter 6, 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 Doopliss.
** Bowser actually pulled the Space Flea bit first in this game. ''Twice'', in fact. The first time he appears during the Glitz Pit tournament, where he appears out of nowhere to challenge Mario to a fight immediately following another ranked fight. He appears again near the end of the game [[spoiler:while you're fighting the BigBad Grodus! He and Kammy literally drop from above without warning and knock Grodus away and immediately start a fight with Mario and company.]]
*** There's also the three giant Bloopers in the first 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.
*Many of the bosses from ''TheLegendOfZelda'', at least in terms of storyline. However, they are vaguely thematically related to the dungeon they appear in. The final boss generally makes sense, though.
** In ''Twilight Princess'' the last of the twilight bugs carrying the Tears of Light randomly turns out to be a ''literal'' giant space flea.
** All of the four main bosses in ''Majora's Mask'' are exempt from this save one: a giant frozen robot goat. A ''giant''. ''Frozen''. ''Robot''. '''''Goat'''''.
* ''{{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 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.
* Verminator, of ''[[WorldOfMana Secret of Evermore]]'' definitely qualifies as a Space Flea. None of the {{NPC}}s mention him, before or after the fight, nor are there any other hints of his existence. He just shows up out of nowhere as you're exploring Ebon Keep. He's one of the toughest bosses in the game, and there isn't much of a reward for defeating him aside from just being rid of him.
* {{Lampshaded}} in ''{{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 ''SuikodenIV'', at the climax of the game, you fight [[spoiler: a [[GiantSpaceFleaFromNowhere Giant Space]] ''[[AWorldwidePunomenon Tree]]'' [[GiantSpaceFleaFromNowhere From Nowhere]]. [[ItMakesSenseInContext It's actually explained]] in the game's {{Backstory}} -- and [[SuikodenTacticsRhapsodia 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.]]
* A whole bunch of these pop up in ''ChronoTrigger'', more common as you approached the end (Giga Gaias, the Golem Twins, etc.). Particularly distracting is the cave near Medina, which exists exclusively to provide a BossBattle. Ironically, the game's ''[[EldritchAbomination literal]]'' [[FinalBoss giant space flea]] is well-integrated into the plot.
** Giga Gaia is probably the worst, given that it randomly appears without any dialogue mentioning it before or after the battle. At least the Golems were established as being Dalton's minions (he sics one on you in the throne room, then two in the Ocean Palace).
** And let's not forget Black Omen, where its essentially a breeding ground for Giant Space Fleas sans the first boss battle. Its so bad even the Mooks become space fleas.
*''NinjaGaiden II'' 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 he block button. This basically guarantees that players will die at least once from it.
** It's actually a part of the ship, presumably the main core. However, you likely won't hear the references to it on the ship unless you have the subtitles turned on, and the scene of it emerging from the wrecked ship is so blink-and-you-miss-it quick that most players assume that it just came out of the ground. So, it still qualifies.
*** You can even see the thing about midway through the stage. It's balled up in the background of one of the hangar-like rooms (a cut-and-paste of the one where you fight Genshin).
* The Kelbeross in ''NinjaGaiden NES''.
* After you defeat the BigBad in the arcade version of ''Astyanax'', who is a ShoutOut to Emperor Palpatine from ''StarWars'', complete with "force lightning", you suddenly find yourself in the true final stage, which is a technorganic alien hive complete with eggs and facehuggers. At the end, of course is the "Queen Alien", which obviously looks like a Xenomorph from the ''Alien'' movies. Space Flea Hive Level From Nowhere?
** The same thing happened in virtually every game in the ''Turrican'' series. The penultimate or final level would always be a Xenomorph hive straight out of ''Aliens'', complete with face-huggers aplenty. Needless to say, Xenomorphs have nothing to do with the plot of any game of the series.
* Chernabog from ''KingdomHearts''. He 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.
** He's there because [[{{Fantasia}} Bald Mountain]] got wiped out and he has nowhere else to go, and nothing else to do
** And quite obviously, RuleOfCool.
* In the series finale of ''{{Thundercats}}'', after Lion-O fights an epic final battle against his ArchEnemy Mumm-ra, the Evil Spirits randomly throw "their champion", a giant warrior named Pyron, at Lion-O just to fill up the last couple of minutes or so of the episode.
* ''CastleCrashers'' also does this in the final level. Even though the Cyclops and BlackKnight are both encountered in earlier levels, on the final level you fight a guy with a toolbox for a head that draws bad flash animation.
**The paint guy was shown carrying the fourth princess just before the sequence where you chase the flying castle.
* The Japanese version of ''Frankenstein Conquers The World'' climaxes in a fight between FrankensteinsMonster and a giant octopus with no plot relevance. The scene was cut from the English dub.
--->''Human guy'': "Oh my God! That's a giant octopus!"
*The platformer game series Turrican LOVES this trope. Most of the bosses don't fit into whatever plot the games have. (Giant alien monster, flying ram with laser cannons, etc.) A few examples includes [[http://www.nemmelheim.de/turrican/other/turrican1/show.php?file=images/level1/TurricanI_024.png&w=608&h=430 this]] [[http://www.nemmelheim.de/turrican/other/turrican1/show.php?file=images/level2/TurricanI_040.png&w=608&h=430 this]] [[http://www.nemmelheim.de/turrican/other/turrican2/show.php?file=images/level1/TurricanII_0034.png&w=608&h=430 this]] [[http://www.nemmelheim.de/turrican/other/turrican2/show.php?file=images/level1/TurricanII_0045.png&w=608&h=430 this]] [[http://www.nemmelheim.de/turrican/other/turrican2/show.php?file=images/level3/TurricanII_076.png&w=608&h=430 and this]]. Not even the [[http://www.nemmelheim.de/turrican/other/turrican2/show.php?file=images/level5/TurricanII_117.png&w=608&h=430 end boss]] of Turrican 2 looked like the Big Bad you saw in the [[http://www.nemmelheim.de/turrican/other/turrican2/show.php?file=images/intro/TurricanII_000_intro_14.png&w=608&h=430 intro]]. Fighting him [[spoiler:happens in the third game though.]]
* The Sega Mega Drive game Alien Soldier IS this trope. ENTIRELY. Nearly every enemy (enemy in this case being equivalent to a boss in every other game) is unexplained save for a few, usually ungodly powerful, and progressively stranger (giant crabs in an airport, a giant cyborg wolf cowboy with a machine gun arm riding a robot horse that can crawl, etc). You cannot go longer than a minute or two without running into something giant, random, and unexplained.
* None of the bosses in ''TheGuardianLegend'' really have a connection to the plot, but the stand-out Space Flea From Nowhere boss is the FinalBoss "It", a cyclopean tentacled monstrosity which suddenly confronts the Guardian in outer space after she's escaped from the asteroid(and endured a BossRush).
* ''{{Castlevania}} Aria of Sorrow'''s Good Ending. Soma Cruz decides to [[EnemyWithin fight the force of Chaos trying to subvert him.]] Its form? Is it [[BigBad Dracula?]] [[ThatOneBoss Death?]] No it's a snake...thing with four gems shooting at you. And um, three statues? We call it "the last boss {{Contra}} forgot."
** The final boss in the sequel Dawn of Sorrow also qualifies, since no one expected [[spoiler:it to burst out of Dmitri's body as a fusion of all the demons he dominated]].
** It's fairly similar, in look and style, to the Parasite boss of ''Lament of Innocence'', though still incredibly random.
* The TransformingMecha "Mr. Heli Robo" in ''Contra: Shattered Soldier'', which first momentarily appears as a BaitAndSwitchBoss in Mission 1 before getting crushed by the mutant turtle. Then it comes BackFromTheDead at the beginning of the first TrueFinalBoss stage.
** The Relic of Moirai himself may count as one too.
* ''{{Metroid}} Fusion'' has a Security Drone that you face in PYR. It is the only boss in the entire game not infected with an X-Parasite and it doesn't even give you an item (the item you get during that period, the Super Missile, comes right beforehand). However, it does become more relevant when you face it a second time later on in the game and it IS infected.
** In ''Metroid Prime 2'' is the Caretaker Class Drone, the only boss in the game that is not in any way related to the Ing and was only built by the Luminoth to test out their Boost Ball technology. It doesn't give you any items either, so its situation is almost exactly like the Security Drone in ''Metroid Fusion'', only it doesn't end up falling prey to the Ing by the end of the game.
* Mr. X, the ImplacableMan in the second scenario of ''ResidentEvil 2'', to some degree. At first, he appears out of nowhere and seems to have no purpose in the plot, but towards the end it is revealed that he is after a sample of the G-Virus.
** It's strongly hinted throughout the game that Mr. X is a modified and perfected Tyrant model, a Tyrant being the final boss of the first game; so it's not really that much of a surprise.
** The first Garrador (Blind Slasher) in ''ResidentEvil 4'' 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.]]
** The odd insect-like boss that attacks in Chapter 5 counts, too, since none of the reports seem to hint at it.
** The titular BigBad of ''Nemesis'' may even fit this. Only thing important is that "He's after STARS members!"
* The StarFox series loves this trope, particularly the 64 iteration. Nearly all of the level bosses just suddenly show up with little foreshadowing or dialogue to announce who or what they are until they actually appear.
** ''Star Fox Assault'' has Giant Space Fleas from Nowhere become the main villains of the game.
* ''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.
* ''[[CapcomVsWhatever Marvel Super Heroes Versus Street Fighter]]'': The seventh round is Apocalypse, fair enough... 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]])
** If you said that [[{{Okami}} Yami]] would be the boss of ''Tatsunoko vs. Capcom'' prior to its release, everyone would be mocking you.
*** After the boss battle, do they talk about their achievement? No, they do a completely different task, ''[[{{BigLippedAlligatorMoment}} and they never mention fighting Yami again]]''
* The Queen Spydor of ''Chibi-Robo'' is both a space flea in terms of plot and in gameplay, in that it appears out of near-nowhere in the finale and is a boss in a game where combat is practically non-existant....and it still manages to fit into the whole thing fairly well and be completely awesome.
* So you're playing ''{{Secret of Mana}}'', wandering through a lovely ice forest and enjoying the serene music. Then as you cross to a new screen, you run into Boreal Face, a boss that not only looks [[PaletteSwap suspiciously similar]] to a previous boss, but is completely unexpected and completely irrelevant to the plot.
** Most of the bosses after Matango, with a few exceptions, are either related to the [[EvilEmpire Empire]] or Giant Space Fleas From Nowhere, the latter of which is especially present in the Gold Tower.
* Pretty much every single boss in ''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. I'd list more, but the sheer number alone would hurt my brain.
* Kil'jaeden, the FinalBoss of the first ''{{World of Warcraft}}'' 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. Despite this, Sunwell Plateau (where you fight Kil'jaeden) is widely considered a CrowningMomentOfAwesome in terms of dungeon design.
** 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.
** Come to think of it, all of the Elemental Lords can be considered this. The players decide to take out Ragnaros the Firelord just because he's there, and his only objective is to kill the much more evil dragon at the top of the mountain. Then you have C'thun. It seems that Blizzard had decided that they had better make that barren wasteland that has nothing significant in it useful by opening up a raid dungeon. Even when going in there, you would think that the BigBad of the dungeon would be a giant bug...but it's an EldritchAbomination whose name hadn't even been so much as mentioned up until that point.
***Again, it makes sense if you pay attention to the backstory. The Old Gods are [[SealedEvilInACan sealed evils in cans]] left by the {{Precursors}}, who are presumably upset about the Titans remaking their world. Ragnaros (who had been previously mentioned as one of the lieutenants of the aforementioned SealedEvilInACan) himself gets tons of lore in the surrounding zones, which are [[EvilIsNotAToy ''on fire'' because of his summoning]], which was done by the Dark Iron Dwarves because they felt pinned between Ironforge and the Wildhammer dwarves in the Hinterlands, because they started a civil war, because of various kings killing each other, BlahBlahBlah. This backstory is spread out all over the continent, because frankly about a third of it (the center) is being menaced by him. The quest chains start around level 20 and persist until 60. It's a massive story arc.
*** Deathwing could maybe be considered one for the upcoming third expansion, ''Cataclysim'' as the only time he was mentioned in the current storyline was a short scene during a boss fight with the other {{Eldritch Abomination}}, Yogg-Sauron, and that was in his human disguise.
***Deathwing makes sense to those who played earlier games and know the lore, however. Unfortunately, most of the 11 million don't follow or care about the lore (probably why most of it is now on the cutting room floor).
* Arguably, Blues/Proto Man's first appearance in ''MegaMan 3'' qualifies. He made sense later on, but that first time, he was just kinda...''there''.
* ''ShiningForce II'': The Kraken. There might have been passing mention of a sea monster, but this fight occurs in a river. It's at a junction in said river, and the fight comes out of nowhere. It doesn't hurt that this fight is so much harder than anything before or afterwards, so much so that it's probably one of the few cases of SequenceBreaking by the AI of a video game. If the BigBad actually sent the Kraken or something, it's one of the few times a video game villain actually did something fairly logical with their immense power (i.e. blitzing the heroes before they can level up).
* Apocalymon, the final villain of the original {{Digimon}} series, literally shows up out of nowhere in an outer space-like battlefield, and is fought and defeated within the course of two episodes.
* The Granstream Saga [[spoiler:manages to produce a boss from nowhere, tying it into the plot while simultaneously nullifying the rest of the point of the game]], which is a bit of an achievement. After you've happily completed the game's quest across four floating continents to save them from falling into the sea, [[spoiler:you're sucked into a black hole where you're told by somebody called Demaar 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.
* The classic Comicbook/{{X-Men}} arcade game inexplicably throws [[Comicbook/TheAvengers Avengers]] villain Ultron at you at one point, despite having no relevance to the story and no dealings with the X-Men in the comic book.
** Actually the boss is indeed an X-Men villain, a Sentinel known as Nimrod. It still doesn't make any sense why he would be working for Magneto though, 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 attack you in the tomb wihtout any foreshadowing, and earlier on in the level, the players get attacked by six weak clones of Pyro.
* The third boss in the freeware game ''Assassin Blue'' arguably qualifies. Up to this point, the game has been consistent with a realistic setting, with some fantastic bits, but is for the most part low-fantasy. Then comes the third boss, [[spoiler:''a floating stone head that shoots lasers''.]] It certainly doesn't fit what was in the game before it, or indeed after it, and the battle and the level it's in feel incredibly tacked-on.
* The boss of the Sandopolis zone act 1 from th 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. Yeah.
** The strange robotic Sonic (who seems different from Metal Sonic) in Sky Sanctuary Zone definitely counts, especially since it's the '''final boss''' for Knuckles.
* The giant fish boss in ''GearsOfWar 2'' is essentially this, not being referenced at all in the storyline beyond some foreshadowing immediately before its arrival. It gets away with it by being [[RuleOfCool awesome]].
* Non-videogame example: the 'BigBad' in [[TheDCU DC's]] "[[CrisisCrossover Final Crisis]]," WASN'T Darkseid. It was a [[spoiler: Multiversal Vampire. This means exactly what you think it does: he eats stories. His existence apparently showed up in ancillary material. This could have been forgivable since Word Of God stated that because of the depth of story there were two categories of 'ancillary' the 'tie in' and the literal supplements (which were identified as such by the cover design and the prefix 'FINAL CRISIS"). Which would have been fine, except they weren't. 'Rage of the Red Lanterns' fit the guide as a 'supplement' yet had no connection to Final Crisis at all.]]
* The [[spoiler: Biolizard]] from ''[[SonicTheHedgehog Sonic]] [[SonicAdventureSeries Adventure 2]]'' could half-count as a GSFFN. Some earlier context mentions a prototype ultimate life-form, but never actually refers to what it is (though all is explained after the battle). Imagine running through a space station to turn off a giant death-ray that was on a timer to destroy the world in an hour, reaching the control room, than seeing a giant orange lizard on life-support appear in a flash of light 3 feet in front of you. Then, once you fight it, you find out about one-tenth of the information needed to understand its existence, and it teleports away so that you can [[spoiler: fight it while it's mixed with the previously mentioned death ray.]]
** It did appear briefly in the Dark Side story. Look closely at the picture Rouge finds when she's examining the data from Project Shadow.
** If anything, King Boom Boo fits this trope perfectly. Seriously, 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?
*** It was a GiantSpaceFleaFromNowhere for the sole purpose of an EigenPlot - the only boss battle you fight as Knuckles which isn't a [[RyuAndKen rival character]]. Of course, it doesn't explain why Tails never gets one of these when EVERY OTHER CHARACTER, even Eggman, does.
* Nearly every boss in ''{{Mother 3}}''.
* EVERY SINGLE BOSS in ''LightCrusader'' except Bloodroke and Ramiah/Huster.
* ''Seiken Denesetsu 3'''s final bosses are all giant space fleas form nowhere. The player defeats one of the three villains they originally set out to defeat only to have someone else be summoned or appear and destroy them. Oh guess who's the final boss?
** Um, what? Did you play the same game I did?
* Surt of ''ValkyrieProfile'' didn't really have any build-up, but that more or less assumes you know Norse Mythology and knew who he was.
* [[spoiler: Heinrich]] from ''ConkersBadFurDay''.
* As depicted above, the final boss from the hideous brawler ''Growl'' might be the ultimate example of this trope, since the game is all about beating to death hordes of poachers and freeing captive animals. When you take out their leader (a masked freak with enough strength to throw you a friggin' tank) his corpse begins to slither around the arena and then A GIANT MILLIPEDE BURSTS OUT OF HIS BACK. AND THE GAME EXPLAINS THAT IT'S THE TRUE LEADER OF THE POACHERS. Seriously, what the hell???
* ''BatenKaitos: The Eternal Wings and the Lost Ocean'' had several other-dimensional worm.. insect...opoids...things which would break trough into "our" reality where the barrier was weak.
* ''PunchOut (Wii)'' has one when you get to fight a hidden boxer. [[spoiler: DonkeyKong. Yes, the same Donkey Kong who beat up Kremlings and played with Mario in sports and go karts. He has no relations to the Punch Out franchise at all.]]
**[[spoiler: He's in the audience of the arcade PunchOut games so it's not's completely random. It's certainly unexpected though.]]
***[[spoiler: And if Mario can ref, why not?]]
* ''{{Alone in the Dark}}: The New Nightmare'' features a battle with a [[NightmareFuel nightmarish]] Insectoid Winged Demon from Nowhere {{mini boss}} in the Library.
* ''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 thy King! Kosher Zombie Mad Cow, God of Hellfire! All bow down, and worship my asscock!". The Postal Dude promptly lampshades the trope by stating "Some designer has lost his tiny mind".
* ''{{Winback}}'': Jin, the ninja 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 ''Razing Storm'' is an enormous skull-shaped battleship. Then again, the rest of the game's plot made little sense.
* GuildWars has one of these in Eye of the North (the Disk of Chaos) It has a unique model, is one of the highest damage and hit point creatures in the game, with regeneration, and is never mentioned before or since.
* In DoubleDragon II's arcade version, the purple Lee Brother ghost is one, as it comes out after the players defeat [[BigBad Willy]]. The mysterious warrior in the NES version is another, as he's never hinted at before.
** The final boss of the NES version ''is'' hinted at, but this is a case of AllThereInTheManual.
* "Caduceus", the final boss of ''{{Strider}} 2'', not only pops out of nowhere with no explanation or relevance to the (admittedly paper-thin) plot... but is in fact gigantic, fought in outer space, and unmistakably flea-like.
* ''{{Beyond the Beyond}}'' has Akkadias as the final boss, who is not mentioned anywhere prior in the entire game. The rest are all plot-relevant.
* "Spider-man"(yes, [[SpiderMan THAT]] Spider-man) is a boss fight in ''Revenge of {{Shinobi}}''. The only foreshadowing of this is a 'Copyright of Marvel Comics' at the beginning of the game.
** {{Batman}}, {{Godzilla}}, and a {{Terminator}} were also bosses in some versions of the game. Seems like Sega liked NoCelebritiesWereHarmed.
** Spiderman also had a cameo as a regular enemy in the original ''{{Shinobi}}''.
* The six-armed muscle-bound mutant in Level 17 of the SNES ''PrinceOfPersia'' seems to have no relation to the rest of the game. It is the only boss other than the BigBad with a unique BattleThemeMusic, suggesting it would be TheDragon or a ClimaxBoss, but it is actually fairly easy, all it does is jump around and cause easily-dodgeable skulls to fall from the ceiling. And it's the only enemy that doesn't appear in the manual.
*Most Bosses from ''BlueDragon'' don't really tie into even the countless sub-plots, and no one bats an eyelash after slaying them.
* 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?''
** Chrono Cross has a lot of these, everything from a giant parrot to a ships steering wheel with a mechanical face that sprays white attacks for some reason. But the icing on the nonsense cake has to be in the sewers of viper manor in home world, where your party is attacked, for absolutely no reason with no foreshadowing, by a literal giant flea. It carries smaller fleas on its back and uses them to attack you.
* The FinalBoss of ''Aero Fighters 2'' is a giant living tablecloth/bedsheet ghost.
* The roaming legendaries in ''{{Pokemon}}'', once unlocked, can be found absolutely anywhere in the world and change location at random. You're just sitting there, training up your Golbat whe. - HOLY CRAP! A RAIKOU!
* ''{{Runescape}}'' 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.
* 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 clown's head on a boot, a fire-breathing ent and, as a final boss, a pair of sphinxes. However, it's Sachen so what do you expect.
* ''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 Touhou fighting game ''TouhouHisoutensoku'' 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 her, however, 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.
** However, 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...]]
* The Kelbeross (demon dog with a DopplegangerAttack) in ''NinjaGaiden NES''.
* The Kalhar Boss Monster in ''Super Star Wars''. Neither a KingMook (Mutant Womprat), nor a pet of the enemy (Jawenko), nor an Imperial guardian (Hover Combat Carrier), nor a monster from the movies (Sarlacc). Just appears out of the blue to block you from meeting Han Solo.
* The almost forgotten SNK side shooter ''[[PrehistoricIsle Prehistoric Isle in 1930]]'' has the some of the usual StockDinosaurs as boss encounters, except the fourth one which is appropiately named "Unknown dinosaur": Part plant and part whale.
* The ending to [[spoiler: Borderlands]].
* The FinalBoss of ''RogueGalaxy'' is a ''very'' odd (and '''frustrating''') 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 BigBad (who is HERSELF a GiantSpaceFleaFromNowhere) 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. Which leads to '''[[MarathonBoss EIGHT. MORE.]] [[ThatOneBoss FINAL. BOSS. BATTLES.]] [[SequentialBoss AFTER. THE. PREVIOUS. TWO.]] [[NintendoHard WITH. NO. SAVES. BETWEEN. THEM.]] [[GoMadFromTheRevelation AAAAAAAAAAAAAAAAAAAAAAAAAAAAARGH.]]'''
* The third chapter of ''TraumaCenter'' has an extremely random [[UnexpectedGenreChange bomb-defusing mission]], followed shortly thereafter by an even more random mission where Derek operates on a patient in an airplane during mid-flight. Apparently, they were thrown in to break up a chapter that was mostly dialog scenes.
* A ''lot'' of the bosses in ''LastScenario''. Some (generally the more human ones) at least merit some acknowledgment by the characters, but others (say, [[ThatOneBoss the Vivionnes]]) are ''[[BigLippedAlligatorMoment never mentioned again]]'', even if they killed off half your party.
*{{Iji}}'s Komato Sentinel Proxima. It's a security robot. A very tough security robot. With an [[BFG MPFB Devastator]], a [[InfinityMinusOneSword Plasma Cannon]], and a [[ExactlyWhatItSaysOnTheTin Nuke]] (and a few lesser weapons). And that's just about all it is. However, it is mentioned afterward, both by Iji explaining to Dan and [[spoiler:if Dan dies]] by the Komato in their list of astonishing and disruptive things you've done.
* In {{Fable}}, 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.
* SigmaStarSaga gives us a few of these, including some ''literal'' giant space fleas from nowhere.
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