Unique Enemy

A video game trope you've seen a million times: an enemy, just a plain old enemy that inexplicably turns up only once in the entire game. You wonder why the developers coded it; you wonder if it was partially Dummied Out. Sometimes it's just there to provide a special challenge for anyone trying for One Hundred Percent Completion. Sometimes it's there because it exists to fit a unique circumstance in a level or sidequest. Whatever the reason, it's unremarkable in most respects except that it's just there the one time.

There are two types of this, broadly speaking: enemies who appear only once in an entire game, and those who appear a very few times in only a single level or screen of a game. For whatever reason, Metroidvania games seem prone to containing Unique Enemies. Mods and romhacks will often feature this enemy more often, especially if it has a good gimmick.

Please try to avoid listing minibosses and so forth here; these enemies are notable primarily because they're regular enemies who could by all rights turn up at various points in the game but don't.


 * Super Metroid has a few in Maridia, mostly for functional reasons: In one corridor, a bizarre walker carves a path through a wall for the player. Later in the same segment, a corridor contains a squirming pile of white...things to help show off one of the abilities of Samus' new found equipment.
 * Maridia also has a large turtle-like creature accompanied by little baby turtles. Its purpose is to help reach a missile pack that would otherwise require Space Jump (which you only get later) to reach. There's also the mysterious orange Zoomer in crateria, which looks like a normal Zoomer exept it's orange, only appears in one room in a place you can't reach, and keeps following you around as you move. It can be killed with the Wave Beam, just as easily as any other Zoomer.
 * The Dachora and Etecoons can be saved at the end of the game by entering a side room and shooting the wall. No reason other than to help those who helped you. They actually appear again in Metroid Fusion.
 * Ice Shriekbats in Metroid Prime are a famous one-time scan. They only appear in one room in the entire game, they look just like a very common enemy you've already scanned, and they disappear as soon as you get a nearby suit upgrade and never appear again, making it impossible to fill your logbook if you missed them. There are several other one-time scans in this series, too. Thankfully, this is changed in the PAL version.
 * There's also Ice Parasites that only appear in one room and disappear from the game, but luckily they'e not quite as easy to miss as the Shriekbats (for one, they don't fly at you and explode on your face as soon as you get close). Same with the Aqua Drones, which appear in one room and disappear after that.
 * In the sequel, the most interesting example are the Lightbringers, which are living, walking safe zones that crawl on walls. Interesting game mechanic that could have been used in a lot of places... but no, you only got to see three of them in a room near the beginning of the game, and they're gone when you come back later.
 * Also, the Lightbringer's data scan mentions energizing them like a normal safe zone or destroying them with matter-antimatter weapons, but they disappear before you get the Light and Annihilator Beams.
 * Metroid Prime 3 has a frustrating few, including the incredibly hard to scan gel ray.
 * Castlevania Aria Of Sorrow has a couple of ordinary enemies who appear in just one room to frustrate One Hundred Percent Completion, such as the super-fast flying fish enemy that requires a TimeStopper from another Unique Enemy, the Chronomage, just to see and defeat. There's also the almost harmless Tsuchinko enemy, which is an in-joke on a Japanese cryptid/urban legend.
 * Dawn of Sorrow also has a few unique enemies. Three are of the "special requirement to find" (Mothman, Winged Humanoid and Yeti) variety, and there are several others that just happen to have one spawn location in the entire game (such as the Alura Une and the Wakwak Tree).
 * Symphony of the Night has the Dodo bird, who appears in one room and runs for its life the moment it sees you...with good reason, too, as killing it gives you a chance at an Infinity+1 Sword drop.
 * Symphony actually has loads, especially if you consider enemies that appear more than once, but never outside of the one room they're found in.
 * The dodo above re-appears in Portrait of Ruin in a single room... sometimes. It's pretty much random. There are also a few others. Sand Worms in the desert levels only appear once and never re-appear once killed, and there are two palette swapped kinds. A ghoul king only appears after killing ghouls in certain rooms after a certain time, and the giant ghost only appears in a single room after killing ghosts for a certain time. Aside from the sandworms, they're required for sidequests.
 * Oddly, the Stone Rose/Man-eating Plant which is fairly common in later games only appears in one spot in Stage 1 of Rondo of Blood, as well as the hunchback in Stage 3 who tries to steal your subweapon.
 * The glass skeletons only appear in one room in Harmony of Dissonance. They seem to be there to give nice exp.
 * Castlevania examples, as you can see, go on for AGES.
 * The Legend of Zelda A Link to the Past has a blimp-like creature that splits into multiple smaller enemies by the shore of Lake Hylia... and nowhere else.
 * In the same game, the Lynels from the first game appear as but one group of three at the top of Dark Mountain near Ganon's Tower.
 * From the Forest Temple in The Legend of Zelda: Twilight Princess comes a lone medium-sized Skulltulla that dangles over one bridge in one room. Kill it, and it's gone forever.
 * Another Legend of Zelda example: Takkuri, a large bird that divebombs Link and steals Rupees or items from him, is an enemy type in some games but a unique enemy in Link's Awakening and Majora's Mask. Majora's Mask also features a single Blue ChuChu in one small room in the Great Bay Temple.
 * Similarly, The Minish Cap has a single Blue Tektite in its overworld.
 * Also from Link's Awakening is a monkey that lives in one tree on the beach and throws coconuts at you.
 * Link's Awakening also has... Kirby. Yes, that Kirby. As an enemy. He only appears in a single room in the Eagle's Tower dungeon.
 * Ocarina Of Time has the Composer Brothers, which are strange Poe-like enemies that only appear if you open their graves in Kakariko Graveyard. It's entirely optional, and are one of very few enemies to speak with you after being defeated. (However, they have some minor plot significance.)
 * The Anubis enemy is only seen in one or two rooms of the Child Link half of the Spirit Temple, and the Tailpasaran is only found in one corridor of Jabu Jabu's Belly.
 * In Zelda II, just before you fight the final boss battles you walk through a room with in which a giant 'Bot' will appear from nowhere above your head. Given by this point in the game you've learned to upthrust with your sword, and the thing can be broken up with one hit, I imagine most people killed it before they'd fully processed what it was making for a unique enemy with a closely associated sensation of 'wait... what the heck just happened?'
 * Phantom Hourglass had the Pols Voice, which only showed up twice in very specific places in the Temple of Courage. This trope is very common in Zelda games.
 * Majora's Mask has one Peahat hidden in a pit in Termina Field; kill it for a Piece of Heart and you've never got to fight another one. This wouldn't be so unusual had the previous game not featured numerous Peahats of the same type in similar areas.
 * Similarly, normal Poes are only found in one room of the Stone Tower Temple, and a solitary 'normal' (as opposed to Business Scrubs and Mad Scrubs) Deku Scrub enemy is found in the Swamp Spider House. Both of these were a lot more numerous in Ocarina Of Time.
 * Mother 3 has Negative Man, a rather unremarkable and comically-underpowered Joke Character enemy who has a rare drop.
 * He's just the most well known. There's also Fish Roe Man, Soot Dumpling, Mystery Metal Monkey, Bright Smile, Top Dogfish.... There's nearly a dozen more with completely unique sprites that many players may never see hidden in the game. Mother 3 lives this trope.
 * In the NES version of Punch Out, King Hippo is the only boxer without a Head Swap.
 * The Giant Jellyfish in Cave Story shows up on a single screen just to provide an Item Drop without the usual Boss Battle. Oddly enough, you must kill it multiple times.
 * Cave Story also has the mimic door and chinfish, both of which appear once near the start but never again in the game. Basil, an invincible enemy that can one-hit-kill you, only shows up in the undamaged Egg Corridor (although it functions more like a deadly room feature than an enemy), and an exploding green cloud only appears in the ruined Egg Corridor. The Gravekeeper is another unique enemy of no greater significance. Giant Pingon in the same area is also an unique enemy.
 * The blowfish is mentioned in the closing credits as the "only one."
 * There's a character named Mizzo in Super Smash Bros. Brawl that looks like a marionette in a tank. He's only seen once in the game in Adventure mode, but it has a trophy... that details just how there's only one of him in the whole game.
 * Pikmin 2 has a single Toady Bloyster in the Perplexing Pool that holds a treasure. It's the only one you fight in the main game. You fight its bigger boss relative more times than this creature.
 * Weirdly enough, the log file on it shows close to a dozen of them in one place.
 * There are also orange bugs that appear every 30 day in Wistful Wild starting with Day 31.
 * Yoshis Island has many examples that appear in only one castle or fortress stage, such as Bouncing Bullet Bill, Georgette Jelly, Grim Leecher, Piro Dangle, and Kaboomba. Yoshi's Story is similar, with enemies like Blindfold Boo and Barbecue Guy only appearing in one stage. Because all bosses in Yoshi's Island are of the Giant Mook variety (after a Make My Monster Grow sequence), many are based on enemies that appear in the boss's level (long enough to "establish" them as monsters) and nowhere else.
 * As a bit of an Easter egg, killing the one and only Chain Chomp in Yoshis Island (which requires the use of an item, since he can't be eaten, stomped, or killed with an egg) reveals a hidden message block.
 * The level 'Monkey's Favourite Lake' has Barney Bubble, a strange purple creature that blows bubbles when you stomp on it. Only two appear at the very end of the level and nowhere else.
 * Super Mario World had one level with a Lakitu that taunts you with a 1-up mushroom on a fishing pole. Despite its rarity, the fishing pole has since become an Iconic Item for Lakitus in spinoff games, most notably Mario Kart.
 * Super Mario World also had the Fishin' Boo, a rare ghost Lakitu that follows Mario with a flame on a fishing rod. It only appeared for a short while in the first room of the Choco Island Ghost House. The same stage also had a few ghosts that turned into solid blocks when Mario looked at them.
 * One Ghost House also had a degraded version of the Big Boo.
 * The Torpedo Teds of the Soda Lake level, anyone? They appeared in bunches, but thankfully, just in That One Level. It's a hidden level too (which leads to Star Road), so it's likely the first time you'll see them is in the ending roll call.
 * There is only one yellow Koopa in the entire game. Tons of green, tons of red, a fair amount of blue - and one lonely yellow one. In a similar vein, each alternately-colored Yoshi appears in only one or two Star Road levels. (You can turn any Yoshi blue in the SNES version if you find Yoshi Wings.)
 * This is because yellow koopa shells are coded to go into that whacky invincible mode if a koopa is inside. Imagine having to deal with those constantly
 * Strangely, the last special level features a single winged yellow Koopa
 * The blocks that Magikoopa hits with his spells turn into yellow Koopas as well.
 * The single Red Snifit in Super Mario Bros 2 as well. Got its own page!
 * Super Mario Galaxy had the lone Grand Goomba, which was too big to jump on.
 * Galaxy also features only two giant jellyfish enemies in the whole game.
 * Several times in the Fallout series, even if they're basically just re-skins.
 * The shoe-wearing Goombas, notoriously, appear in only World 5-3 of Super Mario Bros 3.
 * Super Mario Bros 3 has a lot of these enemies, including the Spiny Cheep-Cheep and a lone fire-breathing Munchie Nipper (both found in World 7).
 * The Parabeetles are only found in one level of World 5. It seems they were planned to be in more levels, according to the screenshot of a deleted level on the box. There's also a green version in some of the Dummied Out levels.
 * The Fire Brothers are only encountered in a secret part of the World 2 map, carrying the third Warp Whistle, and as a solitary individual in one of the Hand Trap stages in World 8.
 * The laser statues in Bowser's Castle.
 * The Angry Sun in an unnumbered stage of World 2 and World 8-2 (potential Nightmare Fuel in the latter, as it appears suddenly from behind a hill at night).
 * Super Mario World has the Ninji enemy from Super Mario Bros 2 show up only in the last hallway of Bowser's Castle.
 * In Paper Mario: The Thousand-Year Door, there is a type of Yux that you only run into once, guarding Grodus's office; it is by itself in the room and doesn't respawn.
 * Some of the enemies in the Glitz Pit and Pit of 100 Trials.
 * The Fake Bowser found at the end of World 3 of the original Super Mario Bros is actually
 * In the same game, World 7-3 is the only level with flying green Koopa Paratroopas.
 * In Half Life 2, the Claw Scanners appear in a couple of chapters and don't appear again until late in Episode 2.
 * In the original Half Life, the Black Ops assassins only appear in two rooms in the entire game, and even then only in groups of three. In Opposing Force, they're more common, but only slightly so.
 * Kirby's Dream Land 3 has two instances. The first is Polof, a rabbit-like creature that appears in one level of Sand Canyon, and disappears into a background wall when you approach. Though this one actually has a purpose: The second is Batamon, which appears in a few levels and looks a lot like Kirby. Usually there's no way to engage them directly, though in one level there's a secret where you can. There are also certain copy abilities that'll let you destroy them from a distance, but there's no discernible reason to do so.
 * Kirby 64 also has the waddling black enemies, N-Z. They serve as a replacement for the Waddle Dees in the rest of the series (since Waddle Dee is a friend now), and are all set up to be the game's Goomba... ...and then they don't appear anywhere in the game outside of the first level, and the very last section of the last level.
 * In Kirby's Adventure, Rolling Turtle (Phan Phan in the remake) is only found in level 4-4. The only other time you find it is 7-2, which is a Miniboss Rush level.
 * While on the edge of the trope, possibly any enemy that only shows up as backup for the boss in a Boss Battle. There are a lot of these in the Mario RPGs, which only ever appear as a minion for a Flunky Boss.
 * Super Mario RPG has the Ribite, a Palette Swap of the Frogog fought in the first world. It's found only in a hidden cave in Land's End, the fifth world... On top of that, it doesn't appear on the field screen either.
 * A creature called Drill Bit (a recolor of an earlier enemy named Jabit) appears after beating Smithy's first form as an NPC, and nowhere else (they apparently just started production on them when Mario and co. invaded The Factory).
 * Throughout the Pokémon series, there have been several non-legendary species of which only one is available to the player, whether in the wild or through NPC interaction. Notably, some of these species become more common in later Generations.
 * In Generation I, the three starter Pokemon (Bulbasaur, Charmander, and Squirtle) can only be obtained from Prof. Oak. Other unique species include the three fossil Pokemon (Kabuto, Omanyte, and Aerodactyl), Snorlax, Farfetch'd, and Lapras.
 * In Yellow, Pikachu is your starter, and cannot be encountered in the wild.
 * Also, Bagon are only found in one room in all of Ruby/Sapphire/Emerald, and Feebas are only found in certain spots in one river.
 * This could be applied to some of the trainer classes as well, such as the two (and only two, period) police officers in the second generation and their remakes, which can't be challenged to a rematch, and Game Freak game designer and programmer Shigeki Morimoto has a Creator Cameo in Black and White with the unique class of GAME FREAK, named after his employer.
 * World of Warcraft has a few of these. In Utgarde Keep, you encounter several protodrakes but only one with a rider. Gundrak has the Drakkari Inciter, a weak enemy who only appears once in a group of two more common enemy.
 * On a different note, Rare enemies (marked with a silver frame) only appear once every several hours (or randomly in instances) and are generally killed quickly since they drop very useful items.
 * Most dinosaurs aren't (at least commonly) found outside of Un'goro Crater.
 * There are extremely few shark mobs in the entire game.
 * Undead Quilboar are only found in Razorfen Downs.
 * Lord Marrowgar is the only Bone Wraith ever shown.
 * As of Cataclysm, Marrowgar has received a brother bone wraith. Earthrager Ptah.
 * In Nethack, shades and skeletons are moderately-powerful undead who only appear on the level dubbed "Orcus Town".
 * Buccaneros in Wario Land: Shake It! only ever appear once in the tutorial level... and maybe very rarely late in the battle with Large Fry.
 * Also, the evil treasure chests that eat Wario only appear three times in the level Boogie Mansion, are blasted open to get treasure, and don't respawn.
 * Every level in Wario World except for Greenhorn Forest has at least one enemy unique to it.
 * Many enemies in Ps2 Shinobi appears only in bossfights, and they're often a tiny flyer themed with the boss, including fire-breathing heads for Homura, giant snakes for Kurokuda,laser-spitting masks for Yatsurao, shikigami for  and sentient paper charms for Hiruko.
 * The original Dragon Warrior for the NES had a Golem. Oh sure, you can fight Stone Golems later, or Goldmen earlier, but it had only one enemy named Golem. And it was a Beef Gate guarding the town of Cantlin. After you kill it, gone forever, no more to be found at all.
 * That counts more as a Puzzle Boss, as the Fairy Flute makes it significantly easier to defeat.
 * Many examples in Donkey Kong Country 3, often serving as a level's gimmick:
 * Bazza the barracuda shows up in only one of the game's many underwater levels, serving more as barricades to bypass than enemies. The Game Boy Advance remake includes them in some bonus levels, however.
 * The bird enemy Swoopy serves a similar purpose in one of the game's bonus levels. However, you can find just one other Swoopy in one of the early tree-themed levels.
 * Lemguins appear only in the last level of K3, popping out of holes and sliding towards you.
 * Karbines serve as indestructible enemies in the first factory level, hiding in the background while shooting fireballs at you.
 * Kuchuka is a purple barrel that chucks bombs at you, appearing only in the level Pot Hole Panic.
 * Pink versions of the enemy Koin show up in one of the levels in the last world, attempting to push you off ledges with their trash-can lid shields.
 * Minkeys--little monkeys that chuck notes at you from behind barrel-shields--are only seen in one of the second world's levels though, like Bazza above, they made an additional appearance in one of the remake's extra levels.
 * Gleamin' Bream, whose only purpose is to light up dark areas, in "Floodlit Fish".
 * Finally, the remake adds in a ground-based version of the TNT barrel Klasp, which act similar to the Klobba enemy.
 * However, most of these enemies are seen more than once in the Game Boy game Donkey Kong Land 3, which is based off of DKC3.
 * The original Donkey Kong Country had the Rockkrocs in "Stop & Go Station", and the almost completely invincible gray Krushas in "Platform Perils".
 * Donkey Kong Country 2: Diddy's Kong Quest had:
 * The invincible Snapjaw, found in Rise to the Challenge levels "Slime Climb" and "Clapper's Cavern".
 * The Cat-O-9-Nails, which appears in only three levels, one of which has to be unlocked.
 * The rollercoaster riding Klank in "Target Terror" and "Rickety Race".
 * Kackle from "Haunted Hall", another Minecart Madness level.
 * The ghostly Mini-Neckies that show up during the Kreepy Krow boss battle.
 * The faster, pink Krunchas found in "Castle Crush" and "Clapper's Cavern".
 * In F.E.A.R., the Replica Assassins are only fought in the levels "Watchers" and "Point of Entry" (a total of 8 or 9 in the entire game), and one has a brief cameo in "Exeunt Omnes".
 * the Replica Snipers. They are identical (same health, same weapons...) to the regular Replica soldiers, except fror their completely unique suit, and they only appear once: about 8 of them attack you on a roof during the level "Urban Decay", after that they don't appear anymore, not even in the expansion packs.
 * Halo 2 had the "Honor Guard Councillor", which was actually a glitched Gold Elite. This is the only Gold fought on difficulties lower than Legendary. Accompanied by him are a couple Invisibility Cloaked Ultra Elites.
 * In only one room in the final level of the first game do you encounter cloaked Flood.
 * The first level has an uncloaked Stealth Elite, possibly due to a glitch.
 * The "Quarantine Zone" level has a single Sentinel that shoots with Needler rounds instead of the beam ray Sentinels use. According to one of the programmers, it was a rejected concept they forgot to remove.
 * In the first game, Spec-ops Elites only appear on the final level (and at the end of the penultimate level). In 2, they only appear as enemies on Gravemind.
 * Sacred Icon has the Deflector Shields-equipped Advanced Sentinels.
 * Cairo Station has a pair of Elites dual-wielding plasma pistols at the beginning (they don't know how to use charged shots), and an Elite wielding both a Plasma Rifle and Needler at the end. At the end of the underwater passage on Regret, you encounter a group of stealth-cloaked Grunts, which are never seen again.
 * Halo 3: ODST has an NMPD officer who turns on the Rookie because He Knows Too Much on Data Hive. This is the only time you fight an NMPD officer in the game and also the only non covenant enemy in the game.
 * In every level of Halo: Reach, there is a special hidden Elite who will randomly appear out of nowhere in certain areas if you're fast enough in playing the level. These elite, nicknamed "BOB", give you a load of points when killed (to add to your credits if scoring is turned on) and a special medal if your Xbox Live account is linked to Bungie's site, but if you don't kill them fast enough they will disappear. BOBs come in two flavors: Gold Spec-Ops Rangers and completely white, random model Elites, similar to the aforementioned Honor Guard Councillor. The second variety's white coloration is due to a spawning error where the game "forgets" to add the correct color to the Elite character model.
 * There's one point early in the game where you fight a pair of King Kong-sized lizard-gorillas, apparently a form of local wildlife on the planet. They're tougher than normal infantry, but not so tough that you could call them a boss battle or anything. They're never seen or heard of again afterwards, making the whole encounter something of a Big Lipped Alligator Moment.
 * Similar to the BOB's, the first level contains a lone Stealth Elite (different color than the cloaked Spec-Ops Elites encountered later) nicknamed "Bill", which can be spotted just before the moas first appear. If killed, it drops a data pad that can be read. This also may be a leftover from a dummied-out objective.
 * Zealots are only fought three times in Reach, as a group of three at the end of Winter Contingency, as a singleton on Tip of the Spear, and another trio on The Pillar of Autumn accompanying the Field Marshal (not including the two killed in a cutscene).
 * Most of the room-specific enemies in La-Mulana are really minibosses, but there are a few exceptions: Thunderbird in Tower of Ruin, a large white thing that fires lightning downwards; Ba in the Confusion Gate, which looks and acts like a larger version of the Goddamned Bats La-Mulana players all know and hate; and Spriggan in the Chamber of Extinction's upper area, a giant which the player needs to turn into a stepping stone to a higher platform.
 * StarTropics Has Squidos, enemies that only appear in one room in the game. To top it off, they appear shortly after you acquire a Smart Bomb attack, so you probably won't be seeing them for very long.
 * The Politician, a Giant Mook fought at the end of Level 6 in the original Prince of Persia. This isn't technically a boss, as he is only slightly tougher than the regular Mooks. He was made into a proper boss in the SNES version, and replaced by the tougher Gatekeeper boss in the XBLA remake.
 * The first enemy of Level 8 also qualifies. He looks like every other guard but has different AI. Including the fact that he'll never move towards you, so you really have to learn how to step forward and parry.
 * The arcade version of Contra, on the hard and Harder Than Hard difficulty settings, has a pair of SCUBA divers that jump out of the water and attack you with knives at the beginning of the game, and they are never seen again.
 * Target: Terror's Tanker level has a pair of ninjas with nunchucks that deflect your bullets, which are found nowhere else in the game. There's also knife-throwing ninjas, which are rarely seen in 1P mode until the final mission.
 * At the end of the first stage of Time Crisis II, after the semi crashes, a group of gray soldiers with rocket launchers attacks you. Nowhere else do the gray soldiers wield rocket launchers. Also, during the first Boss Battle and nowhere else, there are Aqua Ninjas that periodically jump out of the water. The first game also had knife-throwing guards during the Disc One Final Boss battle, which became recurring enemies in later games.
 * At the start of the Starbase level in TMNT IV: Turtles in Time, there is a robot moving up and down who fires lasers at you. It takes one hit to kill, and no more appear.
 * The first-person shooter Ubersoldier features a single flamethrower-toting, gas mask-wearing soldier in the final level. He can be killed quickly, and never appears anywhere else.
 * Streets of Rage 2 has a number of regular Mooks that have names unique to their respective sprite-palette combos. Examples include a Joseph named "Talk" and a Donovan named "U-3". Killing such mooks will net juicy point bonuses (useful for racking up extends).
 * The Killer Tomatoes in Donkey Kong 64. They only appear in one specific area of Fungi Forest, and after you kill them, they're gone for good. The toy-themed enemies in Frantic Factory are also very rare.
 * There's also the unnamed, clam-like monsters that are found in a treasure chest only Tiny can enter in Gloomy Galleon, and the Red Kritters that only appear in minigames.
 * The beaver creatures are basically The Goomba for this game. However Crystal Caves is the only place you can find them with yellow fur.
 * Serious Sam II (the Xbox port at least) has exactly one ork (which has a different design) that use the plasma pistol as a weapon. It only appears in a secret arena of the sewer level.
 * In the Neo Geo platformer Top Hunter has two unique enemies in the wind stage: a Tatoo guy who dies in one hit and a walking detonator that will eventually go away if you ignore it.
 * Many enemies in Mr. Gimmick are encountered only once.
 * Corsairs from Fire Emblem, which only appear in one chapter of The Blazing Blade and are effectively the same thing as Pirates, down to the same sprite. The only difference: If you hack a Corsair in your team, they can't Promote.
 * In Blazing Blade most enemies are male, apart from representatives of classes that are Always Female like Troubadors. There are three exceptions to this in the entire game: a lone female Sniper in "Valorous Roland" and a pair of female Druids seen in the Hector Hard Mode and only the Hector Hard Mode version of "Cog of Destiny." The Sniper isn't anything special, but the Druids are real bosses in mook clothing, as they're packing status-ailment inflicting staves and have suck a high Magic stat that their attack range for them is 20 tiles!
 * There is only one giant moth in the entirety of Resident Evil 2, in an optional out-of-the-way room in the lab basement. Screenshots of the beta (not RE 1.5) showed more of them in other locations, such as the power room.
 * In Resident Evil 3 Nemesis: Nemesis, there are only two of the Gamma-type Hunter (the froglike ones).
 * In Marathon 2: Durandal, the "mother of all Cyborgs" only appears once, on the level "Sorry Don't Make It So". In Infinity, it became a recurring (but rare) enemy, and they were even more common in the EVIL Game Mod.
 * In the first Marathon, the Drinniols were only used twice in the entire game, on "The Rose" and "Blaspheme Quarantine". They also had a Dummied Out orange Palette Swap, which may have been the source of the "A Good Way To Die" Secret Level rumors. Better yet are the hostile Attack Drones with grenade launchers, that only appear in one level, "Beware of Low-Flying Defense Drones".
 * Marathon Infinity has several of these, due to its ability to use separate physics models for individual levels. For example, in Confound Delivery, there's a Juggernaut that fires bouncing grenades rather than the usual homing missiles. The Vidmaster's Challenge version of "If I Had a Rocket Launcher" is the only level to feature VacBOB Simulacrums. In the final level of the Game Mod EVIL, there's two Giant Mook versions of the Mystics, and in earlier levels, you face a giant Devlin, as well as completely invisible one guarding a nest of mini-Devlins, and a Sentry Gun that shoots a weird oversized plasma projectile.
 * Two Klobbers, which debuted in Donkey Kong Country 2, make a random appearance in one level in DK: Jungle Climber.
 * The Elite Goombule of Mario & Luigi: Bowser's Inside Story. Only two are ever encountered, directly after unlocking the Green Shell attack.
 * The Player's Guide doesn't even bother listing them in the Enemy Compendium.
 * The weird flying jellyfish-like creatures (named only in the manual as "Sentinels") that patrol Tubba Blubba's Castle in the original Paper Mario. They can't be fought, and only act as Mook Bouncers.
 * In Super Paper Mario, most of the space enemies are justifiably never seen outside of Chapter 4. The eel-like creatures are, however it's implied they could basically live anywhere.
 * In some versions of the original Resident Evil (specifically the Director's Cut and Deadly Silence), the player gets to fight a zombie version of one of his character's S.T.A.R.S. teammate (specifically Forest Speyer).
 * Xenosaga Episode I has the Wyrm enemy, which only shows up once during the, cannot be refought, and tends to flee.
 * Xenoblade tends to have a few "Notorious Monsters" per questing area. They tend to look exaclty like certain creatures from that area, but with buffed-up stats. Oh, and when you fight them, the hands-down best song in the game starts to play...
 * Pathways into Darkness has the invincible Green Oozes on "Warning: Earthquake Zone", the flying rats and flying lizards on "See in the Dark" and "Watch Your Step", respectively, and the invisible Wraiths from A Plague of Demons and electrical orbs in the Labyrinth that are not seen again until the Multi Mook Melee at the end of the game.
 * In the PC version of Return to Castle Wolfenstein, which lacked the Egypt prologue mission, the female Elite Guards only appear in the church level (although they also appear regularly in the last few levels on most versions of the game).
 * In the 2009 Wolfenstein, Elite Mooks are extremely rare, especially when you consider that they're only slightly tougher than regular enemy soldiers. For example, there are only about 8 Elite Guards in the entire game, or only about 9 Flamethrower Soldiers in the entire game.
 * Odium has the Hornets and Harvesters - mundane enemies in every respect, save that they only pop up in one combat. The Hornets attack you while you enter the sewers and the Harvesters pop up in the laboratory at the end of the game.
 * Resident Evil Code Veronica has the poison moths in that one corridor, which you unfortunately have to traverse multiple times. When you revisit the area as Chris, they're gone, replaced by zombies. Earlier, in the passage to the seaplane port, there's a group of zombies that inexplicably have Glowing Eyes of Doom. Cyber-zombies?
 * In Crysis, only 12 enemy Nanosuit Soldiers appear throughout the entire game. While this somewhat makes sense from a storyline perspective (Nanosuits costs about 1 million dollars each), it's a bit underwhelming from a gameplay perspective since they're only about as tough as a Covenant Elite, so they could have easily been used more often without being unbalanced, especially in the later levels.
 * There's a type of alien trooper that has a different head crest and is equipped with a freeze ray instead of an ice gun. There are only about 3 or 4 of them in the entire game. Again, they're a fairly standard enemy, so it's not like they make up for their rarity by being much tougher than normal or anything like that.
 * The "Bouncer" Big Daddy enemy that serves as the mascot of Bioshock is actually only fought twice; once on the second level and once on the final level. All other Bouncer-type Big Daddies encountered in the game are the Elite variant, which uses a different character model.
 * Lots of things in I Wanna Be the Guy only show up in one particular place, usually to punishing you for a completely logical action with a Big Lipped Alligator Moment. These include Ryu, a plane, and the Red Snifit himself, armed with a BFG.
 * Neo Garula from Final Fantasy V counts, as it can only be encountered once in the game (and even then, not guaranteed).
 * Sp Forces/Imperial Elite in Final Fantasy VI only appear if you agree to test your strength against Gestahl's bodyguards during the banquet scene.
 * Final Fantasy VII has a fair number of them all over the place. Although many are palette swaps, special mention should go to the unique Elfadunks and Heavy Tank. Elfadunks are tiny elephants found only on the beaches near the Chocobo Ranch, somewhere you'll never need to go. Heavy Tanks are found only in a single screen near the Gongaga Reactor, but at least you can find Titan there.
 * Final Fantasy VIII has enemies called Slappers, monsters in hockey gear that only appear on the hockey court in Galbadia Garden. They don't even get a trading card.
 * The NES version of Teenage Mutant Ninja Turtles the Arcade Game had three unique enemies in one entire stage. The Shogun's stage had Robot Gorilla Ninjas, Robot Scorpions, and Robot Tigers that came to life out of door paintings. After beating these things they never show up again throughout the rest of the game.
 * The snow level earlier in the game had some as well; the hopping mechs disguised as snowmen, snowball-throwing Foot ninjas, and an invincible snow plow.
 * Final Fantasy XII has quite a few.
 * The 80 rare game are exactly that--rare. Generally there is only one zone in the game they will spawn in, they will only spawn one at a time, and they have varying spawn conditions, ranging from simple ones like "30% chance on zone entry" to ridiculous ones like "spawn separate monster, aggro it, lure it to completely random and unmarked part of the map, and rare game will spawn." As for respawning them, a few simply require the normal monster respawn and then fulfilling their spawn conditions again, some require you to leave the entire area and return before you try again, and thirty of them do not spawn again. You kill them, that's it.
 * The Elementals and entites operate on the same principle.
 * Then there are simply enemies who are completely normal, but for whatever reason, there's only one spawn point for them in the entire game--prominent examples are the Darkmare in the Stilshrine of Miriam, the Emperor Aevis in Paramina Rift, and most infamously, the Giza Plains Wildsnake. Weakest of the snakes, does not spawn until you get to its hiding point, completely unremarkable to fight--and its drop is required to make the Infinity+1 Sword.
 * Cassandra's Bodyguard Babes seen during Mission 1-3 in Perfect Dark and in the Bonus Stage "Mr. Blonde's Revenge". They make up a fairly large number of enemies in the former and are almost all the enemies in the latter, but otherwise are never seen.
 * In Super Robot Wars W there's a variation of Beastman Deathhell that only appears in chapter 25 (And only one of them, surrounded by several normal ones). What makes him so special? Instead of having his Dual-Wielding attack, his Nipplebeams have a really high range. While it makes sense to face a sniper enemy on this chapter (The hero team is trapped in the Space Wolf planet's high gravity and thus can't move, leaving them unable to escape long-ranged attacks), this super-Deathhell is never referenced in dialogue and there isn't a need for him to exist (The battleships do his job fine).
 * One room in Chrono Trigger's Black Omen is the only place you'll ever meet four Aliens (Ghajs in the remake); significant because they're one of the few enemies you can charm for Magic Tabs.
 * In Armor Armadillo's stage in Mega Man X 1, there is exactly one batton (the bat-type enemy from the classic series) among the newer, skeletal bats. Notable in that this one Randomly Drops high-potency medicines very frequently, so it can be used to farm for life ups.
 * The third stage of Journey to Silius has the Personal Space Invader known as HumpBot, which fortunately only appears about four times, and is not seen in any other stage.
 * In Killzone 2, only several Elite Shock Troopers are fought, all in the third-to-last level. In Killzone 3 only two of these guys show up in the entire game, as part of the first wave of enemies at the beginning of the last level. It's entirely possible for your allies to gun them down before you even notice them. Killzone 3 also has the Capture Troopers and Hazmat Troopers, Chairman Stahl's personal elites who show up frequently in cutscenes but are only seen a handful of times in the game.
 * Left 4 Dead 2 occasionally spawns Jimmy Gibbs Jr. at the finale of Dead Center. He's basically a extra-tough version of the hazmat zombies.
 * The NES / XBLA version of Bionic Commando has lots of these, including the the helipack soldiers in Area 5, the barrel throwers and RC heli-drone pilots in Area 6, the Mobile Cannons and Helicopters in Area 7, the blue bomb-throwing paratroopers in Area 8 (even better, these are only found in the US and PAL versions), a red version of said bomb-thrower at the beginning of Area 2, and the Construction Soldiers in Area 11.
 * There are a few unique enemies in the Thief series:
 * There is only one Hammerite novice in the entire series, appearing in the Thief: The Dark Project level "Break from Cragscleft Prison".
 * The Thief II level "Precious Cargo" features the only Mechanist frogman in the game. He has protective headgear, a portable light source, and a crossbow, making him extremely dangerous.
 * The standard Mechanist worker only appears in the Thief II level "Framed", but another one appears as a ghostly apparition later in the game, and there is also a character who is simply a Head Swap of the worker.
 * The Spider Bot also appears only in the Thief II level "Sabotage at Soulforge".
 * Tree Beasts, appear (suddenly!) in only one section of the Thief II level "Trail of Blood", and in the Thief: Deadly Shadows level "Into the Pagan Sanctuary".
 * Super C, the NES version of Super Contra, has a single grenade throwing enemy soldier that appears only once in the first stage and is never seen again in any other stage. In contrast, the arcade version has at least three grenade throwers in the first stage.
 * Mass Effect 3 has three examples of this related to decisions earlier in the series..
 * The first Red Faction's one-time non-boss enemies include the APC near the beginning, which you don't even need to fight, the Riot Guards in the barracks, the Ultor Combat Drone in the shuttle bay area, and the adult Rock Worm near the end of Capek's Zoo.
 * The 8-bit version of Sonic the Hedgehog has two enemies that each only occur once: Burrobot, in Labyrinth Zone, and Bomb, in Sky Base Zone.
 * In the Special Stage of Gokujou Parodius, just before the Robot Penguin, you will encounter an enemy called the "16-Bit Block," which has 65536 hit points and will scroll off the screen before you can do any significant damage.