[[caption-width-right:256:The awesomeness of this fight is only completed by [[http://www.youtube.com/watch?v=ZcvJ8nzxH8c this]].]]

Samus Aran has encountered plenty of awesome boss fights in her journeys across space.
* Ridley in any ''Franchise/{{Metroid}}'' game.
** His appearance in ''VideoGame/SuperMetroid'' is unique for the game. All the other bosses have predictable patterns and specific weak points you need to hit to kill them. Not Ridley. He has no weak spots, instead just having tons of health to compensate. He's also by far the fastest of the bosses and zips around the room chaotically. There really isn't much strategy to his fight: just kill him before he kills you. This was the fight that solidified his status as the Awesome Boss of the series. And all of this applies to the revamped Ridley encounter in ''Zero Mission'' as well as Ridley-X in ''Fusion''.
** Especially noteworthy in ''VideoGame/MetroidPrime 3'', where the first Ridley encounter is fought entirely in ''free-fall''.
** The Meta-Ridley battle in the first ''Metroid Prime'' is epic enough when a giant space dragon is bombarding you with bombs, missles, and fire breath. Then, you get his health 3/4 of the way down and, for the first time in the series, we get to see how Ridley fights when grounded. [[ThatOneBoss Turns out he can kick your ass three ways across Tallon IV.]]
** The Mecha-Ridley in ''Metroid Zero Mission'' is amazing. Even with all of the powerups in the game, he remains a formidable challenge, [[note]] Mecha-Ridley's HP and attack damage are scaled up if the player has 100% of the pickups in the game, meaning he's actually easier to beat at 99% collection rate than at 100% [[/note]] attacking with no discernible pattern (using his attacks in any order), with a final phase that can only be described as complete chaos, with missiles and lasers firing everywhere, and an increasingly slim amount of time to fire at his weak point. Not many bosses give off such a feeling of satisfaction after beating them.
** ''VideoGame/MetroidOtherM'''s Ridley fight is also epic, even despite the divisive cutscene before it. Samus basically shits bricks and has to come to her senses when Ridley takes out her friend. Samus kicks his ass anyway, so much so he freaks out himself and crashes through a wall. But that would be leaving out the actual fight. He plays much like the 2D games, as do you - it's fast, frantic, and awesome. It gets even more awesome on Hard mode, where ''almost every attack'' is a OHKO, even the comes-out-of-nowhere tail attack. He also does fireballs at you which cause shockwaves, tries to grab you and drag you against the wall (which he does in a cutscene in ''[[VideoGame/SuperSmashBros Super Smash Bros. Brawl]]''), leaps and flies around, and is generally chaotic. Better still, you've been authorised to use the Super Missiles ''and'' the Plasma Beam literally within a cutscene of this fight, so you get to go to town with your new weaponry.
* ''Super Metroid'' on the SNES, the final fight with Mother Brain. After suffering a huge attack and being brought to your knees, [[spoiler: the young Metroid that you saved in the previous Gameboy installment which thinks Samus is its mother shows up, sucks a bunch of energy out of Mother Brain, and transfers it to you, saving your life and powering you up.]]
** Tearjerker: [[spoiler: The Metroid gets blown up about five seconds after saving your life. Then, [[MamaBear Samus gets pissed.]]]]
** The entire fight is awesome, from beginning to end. [[spoiler: Unloaded dozens of missiles on its head and think it's dead? It rises out of the ground attached to a giant organic robot and the crowning music of doom begins to play. As the battle goes on and you damage it more, it starts releasing even more powerful attacks, finally leading up to that epic laser beam that leaves you on your knees, barely able to move. And then, after Baby saves you and sacrifices itself, the music changes to the theme heard up on the surface, and it sounds perfectly appropriate for the [[CurbStompBattle asskicking]] that you deliver to Mother Brain afterwards.]]
* Metroid Prime, especially on Hard Mode/Hypermode. It has two phases, the first being an armored form that not only requires you to use just about every weapon in your arsenal to beat it down, but also uses said weapons ''against you!'' Being on the receiving end of a charged Plasma Beam blast HURTS. What's worse, it's only vulnerable to one type of beam at a time. You have to constantly switch beams, dodge its incredibly damaging attacks and chase it deeper and deeper into the crater it resides in as it desperately tries to get away from you. Then, just when you think it's over, turns out it has a second form which has you [[CurbStompBattle blasting the living crap out of it with your brand new Phazon beam]], complete with [[http://www.youtube.com/watch?v=42A3uigYXsQ this absolutely epic music.]]
* Quadraxis from ''Prime 2'' is pretty sweet too, being a HumongousMecha and all. It's a different version of the quads you've been fighting all through the Sanctuary Fortress and Ing Hive, except instead of being about your size, it's like 20 times bigger. Then it uses the Annihilator Beam against you, other forms of lasers, spinning attacks, and is just generally huge. After hitting its weak points on its knee joints, it's dismantled. But you're not done yet! Then it tries to repair itself, where you blast the core with beam attacks in Echo Visor mode (yeah, most of the body was destroyed halfway through the fight already) before attacking it's floating head, and THEN after that you finally hit it again a few more times by planting bombs in it's head by using the Spider Ball and Boost Ball up there. After that you're finally done, where the head flies around and destroys everything else, and Samus makes a ThreePointLanding from morph ball mode, while the head bounces around behind her, and the Annihilator Beam appears for the taking. You literally dismantle it bit by bit, and it is epic, with the [[http://www.youtube.com/watch?v=kpQ_OQAtgDQ dark, menacing music]] being the icing on the cake. It's even more awesome if you fight Quadraxis on a [[SelfImposedChallenge No Dark Suit Run]].
* Also from ''Prime 2'': Adultform Chykka. After the hell that is Torvus Bog, a fast and furious fight with a giant mutant dragonfly is just the palette cleanser necessary. After killing the (laughably easy and ''very'' boring) Larvaform Chykka, it turns into a cocoon and metamorphoses in a matter of seconds, then bursts free. The first phase of the fight features you stunning it with your weapons, then blasting its wings off. Then, it falls into dark water and becomes Darkform Chykka, which you kill by...unloading your Light Beam on its egg sac. All the while, it spawns hordes of Chykklings to assault you.
* The Spider Guardian is either a wickedly frustrating ThatOneBoss, or one of these. It really depends on your personality; you have to be ''very'' patient and keep a cool head throughout the fight. Get frustrated or try to rush things and you will get slaughtered.
* [[EvilCounterpart Dark Samus.]] Period. ''Any'' fight with her is pretty much guaranteed to be epic, what with her using your own powers against you ([[spoiler:or, in ''Prime 3'', the other hunters' as well]]), often [[ToxicPhlebotinum Phazon]]-enhanced, and [[http://www.youtube.com/watch?v=VEVQ6JxQFr4 this]] [[http://www.youtube.com/watch?v=QFOqGV-6bck music]] playing in the background. It doesn't hurt that it's a nice break from fifty-foot monstrosities that you have to crawl all over to defeat.
** Or her original form, Metroid Prime. You end up having to use nearly every weapon and even all your visors against this monstrosity of a MarathonBoss, and some attacks formerly thought useless have some use here! (Except [[AwesomeButImpractical the flamethrower]].)
** In ''VideoGame/MetroidPrime 2'', after defeating the Emperor Ing after everything you've been through and all of its three forms and damage you've taken, you're treated to the familiar sight of the escape countdown. The problem? Just as you get out of the Temple, Dark Samus interrupts your escape and starts the true final boss fight. No healing beforehand allowed, and the timer is STILL counting down. Plus you get that awesome escape remix [[http://www.youtube.com/watch?v=C_oNDCY8Nak complete with emergency beeps so you won't forget the timer is still up]].
* Amorbis in ''VideoGame/MetroidPrime 2''. In the higher difficulties, given you have relatively few powerups to find, they're monsters. And that's without going into how awesome it is to kill them by [[{{HSQ}} jamming bombs inside their throats]].
* Flaahgra is similar to Amorbis with the bombing. It is a giant monstrous fly-like plant, which attacks in all sorts of manners, and you have to flip mirrors over in order to get into the tunnels (giant vines guard the tunnels) to damage it with bombs. It is clever enough to flip the mirrors back over, and you're required to flip more mirrors on each hit. This is the first major boss in the game aside from the Parasite Queen, which was just a warm up boss.
* The [[spoiler:Queen Metroid]] from ''[[VideoGame/MetroidOtherM Other M]]'', which definitely delivers as far as 3D boss translations go. Special mention goes to the climax, where you [[spoiler:''blow it up from the inside out with a Power Bomb while your health ticks away like there's no tomorrow.'']]. There's a bit of overlap with ThatOneBoss. While fighting it, you've also got a growing swarm of Metroids during the fight [[spoiler:while you put mommy down.]] This is the first and only time in the entire game where you run into the bastards and they get killed just as you would expect; freeze 'em, and blast 'em with missiles. Doesn't seem too bad, but keep in mind there's a lot of them, and you have to switch to first person to fire missiles. So lets review: You've got to freeze one, stop and leave yourself vulnerable to the other three or four, aim at the one you froze, and hope to blast it with enough missiles before one of it's buddies takes a bite. And if one DOES take a bite. it will drain your health FAST and you probably won't get yourself free before the frozen one thaws. [[spoiler:''All the while avoiding their rampaging mother'']] It does get better as you wear down their numbers, but dealing with them is far from easy. Still all this makes it so satisfying to watch the actual boss get vaporized.
* Kraid from ''Super Metroid''. The first time he explodes you think you've beaten him, then ''BAM!'' the real Kraid appears; where the fake Kraid is barely taller than Samus, the real Kraid is ''two screens tall'', making for an epic confrontation that spans nearly four screens all seamlessly connected to each other while you shoot at him above a pit of spikes. ''And he's only the third boss!'' If you had played and beaten the first ''Metroid'' game, this becomes even more effective. The original Kraid from ''Metroid'' was much smaller, not much bigger than your own sprite. So those smaller Kraids you encounter on the way would have seemed about the right size. The true Kraid must have been a big surprise to Metroid vets.
* All of [[spoiler:The Hunters]] in ''VideoGame/MetroidPrime 3'' double as this and a [[spoiler: TearJerker.]]
* Yakuza, the literal [[DemonicSpiders Demonic Spider]] from ''Metroid Fusion'' is both fondly and [[ThatOneBoss fearfully]] remembered. Something about a Robot Spider that spends its time either spitting fireballs and German Suplexing you... you never forget.
* The SA-X. You've spent the entire game running in fear, hiding in dark corners, trying to keep away from something orders of magnitude more powerful than you. Now, ''it's your turn''.
* In spite of their brutal difficulty, or perhaps BECAUSE of their difficulty, just about any of the boss fights in ''MetroidPrime 2'' could fit this. They can be so controller smashingly frustrating that beating any of them is almost on par with beating a ''VideoGame/DemonsSouls''/''VideoGame/DarkSouls'' boss. Try finding someone who didn't cheer upon watching the Boost Guardian convulsing and expiring.
* In a memorable moment of ''VideoGame/MetroidFusion'', your AI mission control tells you that your only option for accessing your next upgrade at the moment is in a section where one of the station's more interesting specimens has escaped. So what else is new? What's new is that you aren't going to kill this one, because it's an experimental weapon designed by the federation which the researchers nicknamed [[NamesToRunAwayFromReallyFast Nightmare]]. And it will {{Curb Stomp|Battle}} you with your current loadout. As you wander through the damaged sector, [[ParanoiaFuel a shadowy figure darts across the screen]] at random intervals accompanied by [[HellIsThatNoise synthetic screeching]]. Later, you return to the area, to find it completely trashed - the same bulkheads that stand up to the SA-X are torn like tissue paper. And your mission is to kill it because it's going to destroy the station if you don't. All of this is nothing compared to what happens as you fight the thing however - firstly, it is most definitely a cyborg and not a robot. An [[BodyHorror incomplete cyborg]]. As its [[MadeOfIndestructium Indestructium]] armor, GravityMaster powers, and [[IntangibleMan ability to selectively phase through matter]] screw with your ability to even land a solid hit on the thing, you fire away at the [[AttackItsWeakPoint stitched together face]]. And this is where you discover that the [[FacialHorror stitched together organic abomination was in fact a vast aesthetic improvement over the alternative it covered]].