History ThatOneBoss / Metroid

** [[BestBossEver Quadraxis]] becomes one during a [[SelfImposedChallenge No Dark Suit Run]] regardless of difficulty as you '''WILL''' take a ton of damage from both the boss's attacks and the atmosphere of Dark Aether. To top it off, there's not a single safe zone in the battle area just like the fight with the Boost Guardian.

** Chykka is an irritating, [[MarathonBoss long boss]]. The first phase is easy enough, if drawn out, but then it goes downhill fast. The strategy for the adult form sounds simple at first- "stun it and shoot the wings from behind"- but turns into an exercise in patience. The thing darts around to the point where the only way to even have a ''chance'' to hit it is to spam uncharged Power Beam shots, since the shots are pathetically slow and missiles just bounce off. If that sounds hard enough, there's still some attacks that are tough to dodge. And once you actually stun it, it's far too easy to move the wrong way and shoot it in the front, which does absolutely nothing and wastes an opportunity. Once the thing ''finally'' goes down, it releases a huge water wave that is almost impossible to dodge without jumping well in advance. Then it comes up as Dark Chykka. Welcome to the longest boss fight until the final boss in the game. Oddly, this phase is ''easier'' than before, since it doesn't dart around at all and the best strategy is to shoot its inflated eggsac with charged Light Beam shots. It even gives free ammo/health refills with its Chykkling swarms! Even after it comes back up as normal Chykka, it still has ''half of its life left''. It gains new attacks, especially where it flies around, almost impossible to hit. Repeat ''again'', and the thing finally dies. Let's face it, Torvus Bog is full of Those Bosses.

** ''VideoGame/MetroidPrime'' had a cruel bait-and-switch version of this. At first, it just seems like Ridley's gonna fly around, bombarding you with easily-dodgable lasers and missiles. Then, when you get his health down to a quarter, [[OneWingedAngel his wings burn off]] and he shreds through your fifteen Energy Tanks like tissue paper.
** And in ''Other M'', he's not only as melee-happy as he is in ''Prime'', but he also goes invincible at times. The only way to make him vulnerable is by use of a Super Missile, which requires you to go 1st-person and stand still, locking on to him for two seconds straight while he's still attacking you. Note that [[LightningBruiser Ridley has immense reach and speed]], and periodically drops a [[BreathWeapon breath attack]] that hits the whole field. Lastly, get caught in the wrong tackle at the wrong time and [[MythologyGag you'll get a reenactment of their "reunion" in]] ''VideoGame/SuperSmashBrosBrawl''. [[OneHitKill Only this time there's no]] [[{{Franchise/Pokemon}} Pikachu]] [[BigDamnHeroes to save you.]]

** Although it takes less damage than the other bosses, the Omega Metroid can become this if you're not perfectly on time - it deals massive damage, and its attacks cause you to stop for several seconds, which wouldn't even be that bad if you [[TimedMission weren't on a timer.]] The only real way to win is, ahem, [[WebVideo/JonTron touch it real quick and go.]]

** Meta Ridley. He starts out almost hilariously anticlimactic, flying around your platform and throwing bombs, missiles, and lasers at you, all of which are easy to dodge. Then, you get him down to about a fifth of his health, and his wings burn off. He lands and goes into melee mode, where he lunges at you and takes off huge amounts of health with every hit. He also gets much harder to damage, and has to be stunned with a well-timed missile before he exposes his weak spot.

** The Boost Guardian is just aggravating. The fight takes place on Dark Aether, without a safe zone, which means constant, steady damage. The fight takes place in a tiny confined little room. Every so often, the Guardian will shift into a little sphere and rocket around for far too long, careening into Samus with alarming frequency and accuracy. It's completely up to luck however often he hits you. You can go the fight, not get hit once, and then get ripped apart when you've got him down to a quarter health. In addition, it's possible to come out of the fight with too little health to get to a safe zone. It's unlikely, but there's nothing more soul-crushing than having to go through that fight twice. And U-Mos help you if you attempt to fight the Boost Guardian on a [[SelfImposedChallenge No Dark Suit Run]]. The game gives you some BossArenaRecovery in the form of four little pillars that yield 100 energy when destroyed. The problem is that only the Boost Guardian's ball form can destroy them. Sometimes, it'll refuse to touch them when you're down to twenty units of energy and about to die, other times it'll smash all four of them in the first five minutes of the fight and deny you recovery. Also, the destroyed pillars spawn Inglets infinitely.

* The [[FacelessEye Sle]][[CyberCyclops nch]] in ''VideoGame/MetroidPrimeHunters''. Not only are they hard as snot to hit when their giant eyes start flying around, but killing all of their tentacles in order to damage them in the first place is frequently an ordeal in and of itself. The worst thing of all that the eye is moving so fast, and only the pupil will take damage, and you don't have any targeting system to lock on it. It gets even worse when you reach the Slench v3.0, which is positioned at a very awkward angle, and the Slench v4.0, which is on the ''ceiling'' and starts ''rolling after you'' when you kill all its tentacles. After defeating it it's advisable to take a long rest. (To make matters worse you have a timer after each boss battle... at least it creates a checkpoint after you defeat the boss so you're not forced to kill it again.)

** The [[ForkliftFu RB176 Ferrocrusher]] on Hard. Its speed is absolutely ''insane'', and it hits like a sledgehammer. It has a laser which causes explosions wherever it fires. It will grab you with its arms and drill you into the wall for a OneHitKill if you even get close to it. Its charges are very difficult to dodge, and take off massive chunks of your health. Down to the last of your health and need to heal? Too bad, you won't even get a chance until you survive its second phase long enough to freeze its wheels. [[spoiler:Insultingly, the pilot's identity is never revealed, leaving the Deleter plot point hanging.]]

** The Diggernaut's drill arms were a OneHitKill when it was chasing Samus earlier, and in the boss fight they still knock off 150 Energy ''on Normal difficulty''. It can sweep them along the ground, slam them into it to send out shockwaves, and drill into the ceiling to drop gobs of toxic goo onto your head. Its head can fire lasers out both sides, fire laser beams to carve up Samus from the background, and suck up loose debris (and Samus, to the tune of '''300 damage'''). Worse, it has no counterable attacks, the player must be proactive in tearing it apart, and all recovery options cease once both arms are destroyed. The player will likely sympathize with Samus after the fight and run out of fucks to give to the boss by the time all is said and done.
** The Metroid Queen has absolutely no recovery options outside of phase changes, meaning that reckless use of missiles will leave you with only the Ice Beam to win the day with. It can litter the field with energy globules which hurt like hell, fire its lazer along every surface available, roar with enough force to push Samus towards the searing wall, swing its head around to hurt Samus, or some combination of the prior, and it cannot be hurt unless it is spitting something out. On top of that, its only counterable attack only comes between phase changes, meaning you only have two chances to get some free damage in, whether by Super Missiles or by Power Bombs. This fight is ugly as all hell no matter how you look at it, so take it with all due seriousness or expect to see the Game Over screen ''a lot''.

* The ([[NamesToRunAwayFromReallyFast aptly named]]) Nightmare in ''Metroid Fusion'' caused more than one Game Boy Advance to go through a wall. Aside from the huge amount of damage it does to you every hit, it also can inhibit your movement by manipulating gravity.

** The [[ForkliftFu RB176 Ferrocrusher]] on Hard. Its speed is absolutely ''insane'', and it hits like a sledgehammer. It has a laser which causes explosions wherever it fires. It will grab you with its arms and drill you into the wall for a OneHitKill if you even get close to it. Its charges are very difficult to dodge, and take off massive chunks of your health. Down to the last of your health and need to heal? Too bad, you won't even get a chance until you survive its second phase long enough to freeze its wheels. [[spoiler:Insultingly, the pilot's identity is never revealed, leaving the plot point of the Deleter hanging.]]

* [[ArchEnemy Ridley]] is the ''Franchise/{{Metroid}}'' equivalent to Death from ''Castlevania'' - a recurring boss that always makes you want to hurl a controller. To make him even more like Death, when he turned out to be a pushover in ''Metroid: Zero Mission'', fans complained. He WAS hard in ''Super Metroid'', though. Part of what makes him stand out is that while all other bosses have weak points that you can target and fairly predictable attack patterns, there is no trick to fighting Ridley other than to [[DamageSpongeBoss drop his HP to 0 before he does the same to you]], and he has a lot more HP and attack strength than you do. And then there are {{Self Imposed Challenge}}s. Low percent runs or even sequence breaking for the hell of it makes him hard as you have to dodge all his attacks and try to replenish your supply of missiles with a beam that only goes a few pixels.

*** Unless you happen to know the secret that if you stand in the bottom left corner and duck or morph ball it can't hit you except with a fire ball (when it's vulnerable to attack), similar to the same secret with Serris in the bottom right.

** The Boost Guardian is just aggravating. The fight takes place on Dark Aether, without a safe zone, which means constant, steady damage. The fight takes place in a tiny confined little room. Every so often, the Guardian will shift into a little sphere and rocket around for far too long, careening into Samus with alarming frequency and accuracy. It's completely up to luck however often he hits you. You can go the fight, not get hit once, and then get ripped apart when you've got him down to a quarter health. In addition, it's possible to come out of the fight with too little health to get to a safe zone. It's unlikely, but there's nothing more soul-crushing than having to go through that fight twice. And U-Mos help you if you attempt to fight the Boost Guardian on a [[SelfImposedChallenge No Dark Suit Run]].
*** The game gives you some BossArenaRecovery in the form of four little pillars that yield 100 energy when destroyed. The problem is that only the Boost Guardian's ball form can destroy them. Sometimes, it'll refuse to touch them when you're down to twenty energy and about to die, other times it'll smash all four of them in the first five minutes of the fight and deny you recovery. Also, the destroyed pillars spawn Inglets infinitely.
*** The Boost Guardian and Spider Ball Guardian are so infamous for being difficult that, when ''MetroidPrime 2'' was ported to the UsefulNotes/{{Wii}}, they were the only two bosses who were made easier. [[note]]The damage from the Boost Guardian's attacks was toned down and a "Spring Ball" mechanic aided in the Spider Ball Guardian battle.[[/note]]
** [[BestBossEver Quadraxis]] becomes one during a [[SelfImposedChallenge No Dark Suit Run]] regardless of difficulty as you '''WILL''' take a ton of damage from both the boss's attacks and the atmosphere of Dark Aether. To top it off, there's not a single safe zone in the battle area just like the fight with the Boost Guardian.

* ''MetroidPrime 3'' has Gandrayda. Whenever she hasn't taken on the forms of previous bosses/enemies, she jumps around so fast and so much that it's nigh-impossible to reliably hit her; she also tosses explosive energy projectiles and can and ''will'' try to [[PersonalSpaceInvader jump on you]], draining valuable health unless you can quickly shake her off. The first half of the battle is easy, the third quarter is more challenging but still okay, but in the last quarter she abandons the shape-shifting completely, making her extremely difficult to hit, alternates between invisible (which requires you to change visor) and hypermode (which jams the visor and forces you to go hypermode yourself to damage the boss, which can become a problem if your health is already getting low), and it's very possible to accidentally step into the highly damaging acid rain. Also, the only way to regain health is in the ''first phase''.
** Rundas is no slouch, either. He'll speed around the arena while semi airborne, where it's very difficult to hit him with your slow shots and the giant ice pillars he sets up specifically to give himself cover. He also packs highly damaging ice attacks that can freeze you. His hyper mode makes him even faster and can lead to an attack where [[ThatOneAttack he swings around a giant icicle like a flail and throws it at you]], which highly damaging, capable of tearing off energy tanks at a time unless you attack him enough times or hard enough in the short period before he throws it. And to make things worse, [[EarlyBirdBoss you will most likely only have about 3 Energy Tanks at this point.]]

* Near the end of ''MetroidZeroMission'', you fight one of the last remaining Chozo artifacts while in Zero Suit (read: don't have your power suit or any of your advanced weaponry). To defeat it, you need to shoot it four times when it's vulnerable. At any time when it's not vulnerable, it will show mirrored image of Samus, and shooting it will cause her to take damage instead. Sounds simple, right? Don't get used to it. Once you've lowered its health a bit, it will float around the room in increasingly erratic patterns, hoping to do you in via CollisionDamage. It also drops lightning bolts that crawl across the floor and ceiling. So, the final score? It flies around randomly, it hurts to shoot it sometimes, and it makes the environment you face it in lethal. Have fun!
** On Hard, the difficulty spikes considerably: the boss itself and its movements don't change, but because Hard Mode halves the total amount of energy you can pick up (energy tanks now only give you half a full unit apiece) and raises the damage that enemies do, you have a maximum of four and a half full tanks at this point in the game and the boss now does a full energy tank with every hit. Luck will be a factor in your success.
* As you're facing it down, the [[spoiler:Metroid Queen]] in ''[[MetroidOtherM Other M]]'' will spawn a normal Metroid; the only way to kill said Metroid is to shoot it with a charge shot to freeze it, and then aim at it (pointing the Wii remote at the screen and being locked into a stationary first-person perspective) while you charge up and fire a super missile at it. Not a problem until the she starts hemorrhaging so many Metroids that it becomes impossible to freeze some Metroids and charge up a super missile without getting snagged by other Metroids, unless you freeze ALL of them before the first one you froze in the sequence wakes up. This gets easier if you know you can use the 1 button to hold onto a charge when going into visor mode, but still. There's no special tactic, just using sense-move at the last second, firing at the clusters and hoping to god your energy doesn't get too low, because if it does, [[ScrappyMechanic you're fucked]], considering you won't have time in this battle to use Concentration before a Metroid head-rapes you. Then in the second phase, it tosses out heavy-hitting attacks that are almost impossible to dodge. And then the third phase makes you use a technique that you haven't been allowed to use ([[GuideDangIt and don't even know you can use]]) since the opening tutorial eight hours previous, within five seconds or you die. Joy.

* From ''MetroidPrime 2'': The Boost Guardian and Spider Ball Guardian both hold the position of ThatOneBoss for different reasons.

* The [[FacelessEye Sle]][[CyberCyclops nch]] in ''VideoGame/MetroidPrime: Hunters''. Not only are they hard as snot to hit when their giant eyes start flying around, but killing all of their tentacles in order to damage them in the first place is frequently an ordeal in and of itself. The worst thing of all that the eye is moving so fast, and only the pupil will take damage, and you don't have any targeting system to lock on it. It gets even worse when you reach the Slench v3.0, which is positioned at a very awkward angle, and the Slench v4.0, which is on the ''ceiling'' and starts ''rolling after you'' when you kill all its tentacles. After defeating it it's advisable to take a long rest. (To make matters worse you have a timer after each boss battle... at least it creates a checkpoint after you defeat the boss so you're not forced to kill it again.)

** [[BestBossEver Quadraxis]] becomes one during a [[SelfImposedChallenge No Dark Suit Run]] regardless of difficulty as you '''WILL''' take a ton of damage from both the boss's attacks and the atmosphere of Dark Aether.To top it off, there's not a single safe zone in the battle area just like the fight with the Boost Guardian.

** And in ''Other M'', he's not only as melee-happy as he is in ''Prime'', but he also goes invincible at times. The only way to make him vulnerable is by use of a Super Missile, which requires you to go 1st-person and stand still, locking on to him for two seconds straight while he's still attacking you. Note that [[LightningBruiser Ridley has immense reach and speed]], and periodically drops a [[BreathWeapon breath attack]] that hits the whole field. Lastly, get caught in the wrong tackle at the wrong time and [[ShoutOut you'll get a reenactment of their "reunion" in]] SuperSmashBrosBrawl. [[OneHitKill Only this time there's no]] [[{{Franchise/Pokemon}} Pikachu]] [[BigDamnHeroes to save you.]]

** And in ''Other M'', he's not only as melee-happy as he is in ''Prime'', but he also goes invincible at times. The only way to make him vulnerable is by use of a Super Missile, which requires you to go 1st-person and stand still, locking on to him for two seconds straight while he's still attacking you.

** The Boost Guardian is just aggravating. The fight takes place on Dark Aether, outside a safe zone, which means constant, steady damage. The fight takes place in a tiny confined little room. Every so often, the Guardian will shift into a little sphere and rocket around for far too long, careening into Samus with alarming frequency and accuracy. It's completely up to luck however often he hits you. You can go the fight, not get hit once, and then get ripped apart when you've got him down to a quarter health. In addition, it's possible to come out of the fight with too little health to get to a safe zone. It's unlikely, but there's nothing more soul-crushing than having to go through that fight twice. And U-Mos help you if you attempt to fight the Boost Guardian on a [[SelfImposedChallenge No Dark Suit Run]].

** [[BestBossEver Quadraxis]] becomes one during a [[SelfImposedChallenge No Dark Suit Run]] regardless of difficulty as you '''WILL''' take a ton of damage from both the boss's attacks and the atmosphere of Dark Aether.

** [[WolfpackBoss Amorbis]], the guardian of Dark Agon Temple. Their burrowing forms aren't particularly dangerous, but they're hard to track and like to pop out underneath you. After you break the armor of the burrowers, they attach to the alien sphere in the center of the room and gain several nasty projectile attacks, one of which shuts off your safe zones and another one that turns them invincible for a short time. Hillariously ironic, this fight becomes an AntiClimaxBoss on a [[SelfImposedChallenge No Dark Suit Run]] due to the player being much more powerful than what the developers intended for you to be.[[note]]Doing a No Dark Suit run involves leaving Amoris alone until you obtain the Light Suit, which involves completing Sanctuary Fortress and returning to U-mos. There's a long section in Dark Aether that you're supposed to have the Dark Suit for in order to get to Torvus Bog and then Sanctuary Fortress, but that section can be bypassed completely by doing a Ghetto Jump. This is one of the only glitches that was kept in the [[UpdatedRerelease Trilogy Edition]] for the Wii.[[/note]]

** The Boost Guardian is just aggravating. The fight takes place on Dark Aether, outside a safe zone, which means constant, steady damage. The fight takes place in a tiny confined little room. Every so often, the Guardian will shift into a little sphere and rocket around for far too long, careening into Samus with alarming frequency and accuracy. It's completely up to luck however often he hits you. You can go the fight, not get hit once, and then get ripped apart when you've got him down to a quarter health. In addition, it's possible to come out of the fight with too little health to get to a safe zone. It's unlikely, but there's nothing more soul-crushing than having to go through that fight twice. And may U-Mos help you if you attempt to fight the Boost Guardian on a [[SelfImposedChallenge No Dark Suit Run]].

** [[WolfpackBoss Amorbis]], the guardian of Dark Agon Temple. Their burrowing forms aren't particularly dangerous, but they're hard to track and like to pop out underneath you. After you break the armor of the burrowers, they attach to the alien sphere in the center of the room and gain several nasty projectile attacks, one of which shuts off your safe zones and another one that turns them invincible for a short time.,

** [[WolfpackBoss Amorbis]], the guardian of Dark Agon Temple. Their burrowing forms aren't particularly dangerous, but they're hard to track and like to pop out underneath you. After you break the armor of the burrowers, they attach to the alien sphere in the center of the room and gain several nasty projectile attacks, one of which shuts off your safe zones and another one that turns them invincible for a short time. Hillariously ironic, this fight becomes an AntiClimaxBoss on a [[SelfImposedChallenge No Dark Suit Run]] due to the player being much more powerful than what the developers intended for you to be.

** [[BestBossEver Quadraxis]] becomes one during a [[SelfImposedChallenge No Dark Suit Run]] regardless of difficulty as you '''WILL''' take a ton of damage from its attacks and the atmosphere of Dark Aether.

** [[WolfpackBoss Amorbis]], the guardian of Dark Agon Temple. Their burrowing forms aren't particularly dangerous, but they're hard to track and like to pop out underneath you. After you break the armor of the burrowers, they attach to the alien sphere in the center of the room and gain several nasty projectile attacks, one of which shuts off your safe zones and another one that turns them invincible for a short time.

** Dark Samus is a fairly tough final opponent on Normal. On Hypermode? She's unabashedly sadistic. It mostly has to do with the health system you use during the battle, which essentially acts as a combo timer/hit counter, but her attacks are still a pain to dodge and she loves to spam them. And if by some chance you get to [[spoiler:AU 313's head]], it becomes nigh impossible. We're talking four different attacks, and they all take a major chunk out of your remaining energy. At least Dark Samus gave you health pickups...

* Every playthrough of Zero Mission can be a massive hold up on that stupid Zero Suit Chozo boss. The first 3 hits are fine, but the last is nigh impossible to hit due to lack of time frame, and if you're too late it'll hit you instead (that's what it does whenever it doesn't flash vulnerable and it just gets annoying after a while). Let's have a little clarification. Near the end of the game, you fight one of the last remaining Chozo artifacts. To defeat it, you need to shoot it four times when it's vulnerable. At any time when it's not vulnerable, it will show mirrored image of Samus, and shooting it will cause her to take damage instead. Sounds simple, right? Don't get used to it. Once you've lowered its health a bit, it will float around the room in increasingly erratic patterns, hoping to do you in via CollisionDamage. It also drops lightning bolts that crawl across the floor and ceiling. So, the final score? It flies around randomly, it hurts to shoot it sometimes, and it makes the environment you face it in lethal. Have fun!

** There's the Rhedogian (that flying anomalocaris thing), which you have to fight ''four'' [[spoiler:('''six''' if you count the mini-boss rush after the end)]] times. He's really freakin' fast, dodges nearly anything, does heavy damage, has hard-to-dodge attacks, and is invincible most of the time. Also, the first two times you fight it, you have barely any room to maneuver around, and the second time you can get a NonstandardGameOver if you take too long (read: [[GuideDangIt don't know what to do]]) before getting to him. The second battle is probably the worse, as you're stuck in a very confined space with him, so he becomes really difficult to dodge. On Hard, your success depends on when he will try to shoot a giant laser at you. Thankfully, after the third time around you get the Screw Attack, which makes him significantly easier.
** Goyagma, in a WakeUpCallBoss sense. Faced just after a hellish sequence without the Varia suit, Goyagma is easy enough to hit and damage, but his attacks are very unpredictable. He has long arms which he slices across the platform you're on. Sometimes, he'll do it twice. Unfortunately, it can be very hard to tell when to jump as sometimes he swipes slow and sometimes fast, with little to no indication and so you may jump too early or too late. Later in the battle, one of his attacks is a constant hand smash to avoid - but it also forms a mini-eruption where you're at, so you have to get ready to dodge that quickly too. Near the very end, he will do the mini-eruption thing, THEN very quickly follow up with a fast swipe. You won't see it coming. In Hard mode, each of these attacks do 1/3 damage. So that's 1/3 for each mistake, and it's hard to predict against.

** The Boost Guardian is just aggravating. The fight takes place on Dark Aether, outside a safe zone, which means constant, steady damage. The fight takes place in a tiny confined little room. Every so often, the Guardian will shift into a little sphere and rocket around for far too long, careening into Samus with alarming frequency and accuracy. It's completely up to luck however often he hits you. You can go the fight, not get hit once, and then get ripped apart when you've got him down to a quarter health. In addition, it's possible to come out of the fight with too little health to get to a safe zone. It's unlikely, but there's nothing more soul-crushing than having to go through that fight twice.

** Grapple Guardian, which isn't so much ''hard'' as just aggravating to hit at all. First you need to target its eye and damage it until the boss [[TurnsRed gets enraged]]. The eye is rather small, but mercifully is easy to hit. Expect to either spam your basic power beam until your finger hurts or waste your precious light/dark ammo, however. Once you hit it enough, the Grapple Guardian fires the eponymous Grapple Beam at you. If you get hit, you'll take damage as you get closer and closer to it. If it misses completely, you're soon back to the eye phase, during which it takes no "real" HP damage. The trick is to stand behind one of the electrified pillars in the room and let the boss stun itself by grappling it. Once it does you can hit its back, but by the time you've run/jumped behind it you only have a second to act. Firing a Super Missile (as you will want to do) takes almost precisely this amount of time. A 5-shot spread missile is a bit faster, but takes time to lock on instead. Charged beam shots also work, but either drain a lot of ammo or leave you with very little damage dealt. The boss actually gets ''easier'' when it TurnsRed later, since the process for hurting it becomes a lot quicker.

** Depending on your weapons, the [[InvisibleMonsters Cloaked Drone]] can be either a piece of cake or an aggravating encounter. If you took a detour and found the Wavebuster: congratulations! The Wavebuster latches onto the Cloaked Drone and destroys it in three seconds. If you didn't, however, prepare for pain. It can't be locked onto, and the Thermal Visor doesn't reveal it. It's also very possible for first-time players to waste time trying to scan it to no avail and take more damage than necessary. With no way to lock on, trying to shoot it becomes frustrating because you can't aim and run around at the same time, or have to lock your view to one specific point and try to meet it with your shots. [[note]] ''Metroid Prime Trilogy's'' aiming scheme alleviates this a bit.[[/note]] In the meanwhile, it's constantly peppering you with powerful shots and just ''won't stay still.'' To top it all off, the Cloaked Drone is at the end of [[ThatOneLevel 'The Gauntlet']] and is guarding the one save room you've been looking for the past hour. Dying to it makes it even more aggravating.

* [[ArchEnemy Ridley]] is the ''VideoGame/{{Metroid}}'' equivalent to Death from ''Castlevania'' - a recurring boss that always makes you want to hurl a controller. To make him even more like Death, when he turned out to be a pushover in ''Metroid: Zero Mission'', fans complained. He WAS hard in Super Metroid, though. Part of what makes him stand out is that while all other bosses have weak points that you can target and fairly predictable attack patterns, there is no trick to fighting Ridley other than to [[DamageSpongeBoss drop his HP to 0 before he does the same to you]], and he has a lot more HP and attack strength than you do. And then there are {{Self Imposed Challenge}}s. Low percent runs or even sequence breaking for the hell of it makes him hard as you have to dodge all his attacks and try to replenish your supply of missiles with a beam that only goes a few pixels.
** ''MetroidPrime'' had a cruel bait-and-switch version of this. At first, it just seems like Ridley's gonna fly around, bombarding you with easily-dodgable lasers and missiles. Then, when you get his health down to a quarter, [[OneWingedAngel his wings burn off]] and he shreds through your fifteen Energy Tanks like tissue paper.

** Thardus is just dang ''huge'', and thus its attacks hit like a train made of boulders. Most of the time it's throwing boulders at you or curling up and rolling around the room, where it's very hard to dodge because of its size. To damage it, you have to switch to the Thermal Visor, shoot out the highlighted boulder in its body, switch back to the normal visor, and continue blasting away at the highlighted boulder. You have to do this ''a lot''. And as the fight goes on, it summons a ''snowstorm'' that makes it impossible to see more than 10 feet away, which makes it a whole lot harder to dodge its rolling. Annoying and long enough normally... Hard mode is a whole 'nother beast.

*** The Boost Guardian and Spider Ball Guardian are so infamous for being difficult that, when ''MetroidPrime 2'' was ported to the UsefulNotes/{{Wii}}, they were the only two bosses who were made easier.

** And then there's Emperor Ing, the brutal three-form final boss fight. His first form is a massive, immobile creature in the middle of the room that attacks with his tentacles. Destroying the tentacles exposes the eye, the Emperor's weak point. The second form is a cocoon you have to attach to with the Spider Ball and roll all over to bomb its weak points. This form is kind of a breather, since Emperor Ing only has one easily dodged attack. There's also Inglets crawling all over it, which can be killed for pickups. Finally, you have the third form, a gigantic Warrior Ing. He jumps around like a flea, makes huge shockwaves, [[BeamSpam fires beams everywhere]], and gives virtually no opportunities to regain lost health unless you run low on ammo. He's also yet another BarrierChangeBoss, constantly swapping his weakness between light and dark, and requiring you to use the Power Beam to render him vulnerable at all.

** Chykka, which goes from "alright" to "JUST DIE ALREADY", is an irritating, [[MarathonBoss long boss]]. The first phase is easy enough, but then it goes downhill fast. The strategy for the adult form sounds simple at first- "stun it and shoot the wings from behind"- but turns into an exercise in patience. The thing darts around to the point where the only way to even have a ''chance'' to hit it is to spam normal shots, since the shots are pathetically slow (or spam missiles, hope you've been collecting expansions). If that sounds hard enough, there's still some attacks that are tough to dodge (and the seeker missiles are a charged attack so you'll want to dodge). Once the thing ''finally'' goes dow- just kidding, it still has most of its health. As it goes down, it releases a huge water wave that is almost impossible to dodge without jumping well in advance. Then it comes up as Dark Chykka. Welcome to the longest boss fight until the final boss in the game. Oddly, this phase is ''easier'' than before, since it doesn't dart around at all and the best strategy is to shoot its inflated eggsac with charged Light Beam shots. Even after it comes back up as normal Chykka, it still has ''half of its life left''. It gains new attacks, especially where it flies around, almost impossible to hit. Repeat ''again'', and the thing finally dies. Let's face it, Torvus Bog is full of Those Bosses.

*** The Boost Guardian and Spider Ball Guardian are so infamous for being difficult that, when ''MetroidPrime 2'' was ported to the {{Wii}}, they were the only two bosses who were made easier.

** Amorbis, the guardian of Dark Agon Temple. His attacks aren't particularly damaging, but nearly all of them will knock you out of your safe zones, and one of them even shuts off the safe zones for a while. Considering how insanely fast you lose HP on Dark Aether and the fact that you've only got maybe 4-5 Energy Tanks, this becomes a serious issue.

** Chykka, which goes from "alright" to "JUST DIE ALREADY", is an irritating, long boss. The first phase is easy enough, but then it goes downhill fast. The strategy for the adult form sounds simple at first- "stun it and shoot the wings from behind"- but turns into an exercise in patience. The thing darts around to the point where the only way to even have a ''chance'' to hit it is to spam normal shots, since the shots are pathetically slow (or spam missiles, hope you've been collecting expansions). If that sounds hard enough, there's still some attacks that are tough to dodge (and the seeker missiles are a charged attack so you'll want to dodge). Once the thing ''finally'' goes dow- just kidding, it still has most of its health. As it goes down, it releases a huge water wave that is almost impossible to dodge without jumping well in advance. Then it comes up as Dark Chykka. Welcome to the longest boss fight until the final boss in the game. Oddly, this phase is ''easier'' than before, since it doesn't dart around at all and the best strategy is to shoot its inflated eggsac with charged Light Beam shots. Even after it comes back up as normal Chykka, it still has ''half of its life left''. It gains new attacks, especially where it flies around, almost impossible to hit. Repeat ''again'', and the thing finally dies. Let's face it, Torvus Bog is full of Those Bosses.

** Rundas is no slouch, either. He'll speed around the arena at high speeds, where it's very difficult to hit him with your slow shots, and they might get blocked by the giant ice pillars anyways. He also packs highly damaging ice attacks that can freeze you. The attack where [[ThatOneAttack he swings around a giant icicle and throws it at you]] is highly damaging, capable of tearing off energy tanks at a time unless you attack him in the short period before he throws it. And to make things worse, [[EarlyBirdBoss you will most likely only have about 3 Energy Tanks at this point.]]
** Special mention goes to Mogenar, which becomes a long ordeal on higher difficulties. His weakpoints are protected by spheres that he can recharge, and on the highest difficult, they are very hard to destroy, the recharge is nearly impossible to prevent completely, and you'll likely need to destroy each sphere at least twice before you can destroy the weakpoint underneath. And he has 4 of them. And the last one is on his back, so the only way to get to it is to make him charge into a wall and dump a Hyper tank into him while he's looking around. Not that you have any energy to spare, natch - 4 tanks, maybe 5 tops, is about all you can have at that point in the game, and you can't go hyper without having at least one full. That said, with a little practice Mogenar gets easy... except for the part where you have to ''bomb his shoes off''. This requires you to get into morph ball form ''after jumping over a shockwave'', but before he manages to step on you, then planting perfectly timed bombs.

** Chykka, which goes from "alright" to "JUST DIE ALREADY", is an irritating, long boss. The first phase is easy enough, but then it goes downhill fast. The strategy for the adult form sounds simple at first- "stun it and shoot the wings from behind"- but turns into an exercise in patience. The thing darts around to the point where the only way to even have a ''chance'' to hit it is to spam normal shots, since the shots are pathetically slow. If that sounds hard enough, there's still some attacks that are tough to dodge. Once the thing ''finally'' goes dow- just kidding, it still has most of its health. As it goes down, it releases a huge water wave that is almost impossible to dodge without jumping well in advance. Then it comes up as Dark Chykka. Welcome to the longest boss fight until the final boss in the game. Oddly, this phase is ''easier'' than before, since it doesn't dart around at all and the best strategy is to shoot its inflated eggsac with charged Light Beam shots. Even after it comes back up as normal Chykka, it still has ''half of its life left''. It gains new attacks, especially where it flies around, almost impossible to hit. Repeat ''again'', and the thing finally dies. Let's face it, Torvus Bog is full of Those Bosses.

** Yakuza the [[LetsPlay/{{Diabetus}} Kung-Fu Spider]]. Its first form zigzags across the boss room, trying to grab you; if it grabs you, it'll suplex you for staggering amounts of damage. It's only vulnerable at certain times (namely, when it spits fireballs). After you blast its legs off, it gets ''much'' easier, since it loses the suplex attack, gets much easier to hit, and only spits weak projectile attacks.

* As you're facing it down, the [[spoiler:Metroid Queen]] in ''[[MetroidOtherM Other M]]'' will spawn a normal Metroid; the only way to kill said Metroid is to shoot it with a charge shot to freeze it, and then aim at it (pointing the Wii remote at the screen and being locked into a stationary first-person perspective) while you charge up and fire a super missile at it. Not a problem until the she starts hemorrhaging so many Metroids that it becomes impossible to freeze some Metroids and charge up a super missile without getting snagged by other Metroids, unless you freeze ALL of them before the first one you froze in the sequence wakes up. There's no special tactic, just using sense-move at the last second, firing at the clusters and hoping to god your energy doesn't get too low, because if it does, [[ScrappyMechanic you're fucked]], considering you won't have time in this battle to use Concentration before a Metroid head-rapes you. Then in the second phase, it tosses out heavy-hitting attacks that are almost impossible to dodge. And then the third phase makes you use a technique that you haven't been allowed to use ([[GuideDangIt and don't even know you can use]]) since the opening tutorial eight hours previous, within five seconds or you die. Joy.