"If you're at this page, you're either (a) curious, ,(b) heard rumours about Titanic Lance or ,(c) foolish enough to wander into Zone M. If you belong to the first two categories, may this serve as a suitable deterrent to meet him. If you belong to the third category....well, so do I, so I will refrain from commenting on you."
Fatty Glutton in Darius Gaiden. Made even worse in the first game because if you've done well, you may have powered up to the laser, which you need to do to get the Wave later on, but which is worse than your starting weapon.
The Hermit boss of Chapter 3(the Scrappy Level) of The House of the Dead is cheap. A Giant Spider with a very small weak point, that starts out just inches from your face, if you miss here, loss of health is inevitable. This phase has prematurely ended many games. Then it retreats further down the tunnel, becoming even harder to hit, and after being hit it turns its weak point away from you to shoot volleys of web balls at you. The longer you take, the more projectiles will be fired per volley. In the final phase, it guards its weak point until it gets up close and personal, again you have only a split second to hit it before it hits you.
The Heirophant and Sand Area Tower bosses are just as bad; the former has a weak point that's only open for a few seconds, and a diving attack that will always hit if you don't hit its weak point, while the latter hides itself in the sand, only coming up for an attack (and, hence, is the only time you can attack it). Hell, come to think of it, most bosses in House of the Dead can fit into this category, to some extent.
The Fool in House of the Dead III. You need to shoot one of his limbs (marked with a green targeting sight) in order to stop its advance. This is easy enough with his first limb, but his next two limbs tend to get obstructed by the stairs, and his fourth one is used to swing around making it hard to hit. And then his last phase consists of jumping at you to attack, with the only way to stop him being to shoot 6 bullets while it's in the air (you have 6 bullets per reload, by the way). But if you're playing with a 2nd player every boss will have double defense, meaning if the other player is incompetent, being a Jerk Ass, or is simply screwing around, you will lose lives for something that's not your fault.
And the reload is so slow on the PC version that it's actually physically impossible to stop yourself being hit.
Also, taking down first 3 limbs require you to deplete its attack gauge 3 times. If you did it too slow in 1st or 2nd (or both), it's guaranteed that the boss will hit you.
Strength in House of the Dead 2, who on top of brandishing his chainsaw wildly, making his head difficult to shoot, will sometimes jump down from above and immediately take a life off.
Did you enjoy The Magician? Then you'll love The Star, the boss of Chapter 5 of The House of the Dead 4. He bears many similarities to The Magician; he's a humanoid zombie who flies around the arena, fires dozens of energy-based projectiles that need to be shot down lest you lose a life and has two charge attacks, one of which involves GOING OFF THE SCREEN for a moment in a completely dick move that will almost guarantee a life lost. Many players find him to be more difficult than The World, the final boss.
Vampire Night, another light gun game by the same House of the Dead team, features a winged boss that has attacks that are basically a hybrid of Hot D 1's Hangedman and Magician, but who stays faaaaar in the background most of the time. You have to be a crack shot to hurt him any substantial amount before he switches phases and starts circling the player and carving away with a laser.
The first boss could qualify as well. As a helicopter that flies around at the top of the screen and guns you down for standing still (which you need to do in order to fire your gun), it's fairly difficult. And if the battle takes too long (20 seconds or more) he will descend to your level and spam bulletsin your direction. Good luck.
The entire fourth stage in Ikaruga is fought against the level boss, a floating fortress that spends ten minutes hurling ridiculous amounts of enemies and spirograph-patterns of alternating dots at you. Casual players will most likely lack the coordination to switch their ship's polarity in tune with the incoming fire, the return fire from destroyed enemies, and the few enemies who fire on their own to boot. The actual "boss fight" at the end of the level places the player in a tiny space filled with beam weapons that alternate color while firing, and the boss itself is only vulnerable at three (moving) points, all of which have three doors that must be shot through first.
And then there's Tageri's third form in Chapter 5, who fires homing lasers (not unlike yours) at you, alternates polarity, and repeats this process, at an increasingly faster pace. It doesn't help that you whittle his health down, he starts to fire waves of bullets that also alternate in polarity.
Ikaruga's spiritual predecessor, Radiant Silvergun, also features a stage (5A) that is ten minutes against a gigantic flying fortress. Whose walls close in on you while girders scroll down and lasers surround you and enemies come from all sides. Ohtrigen the phoenix also deserves mention for the high speed and number of its projectiles in a game that generally focuses on measured action.
The first half of mission 11 in Project Sylpheed. The difficulty REALLY spikes here, as the Acropolis' armour might as well be paper here, even on easy: first you have to defend against waves of fighters and bombers, and BOTH types can attack the Acropolis. Then, halfway through, the Guilty Roses show up and they're pretty deadly against ANYONE (though if you can pull it off, a well aimed XGS Grav Cannon shot can take all 4 of them out in one shot... but thats only in a second playthrough or later).
Sherudo Garo, the Stage 2 boss and Disc One Final Boss of Time Crisis. He hits quickly with his throwing knives, which have a 100% chance of taking off a life. On top of that, he pops out only momentarily to do this. Most notable in that he's the second boss after Moz, who's a complete pushover. Wild Dog, while certainly a beast, isn't anywhere near a jump over Sherduo as Sherudo is over Moz.
The Dual Boss Tiger and Edgey in the spinoff Crisis Zone. Tiger throws heavy objects and can take a ton of damage, although slow. Edgey, on the other hand, is extremely fast, making him hard to hit before he claws you, and he also throws volleys of knives at you(unlike Sherudo, these can be shot out of the air).
In fact any McNinja type boss in a lightgun shoot-em-up is probably that one boss.
The Stage 2 boss of Time Crisis 3. If you thought ninjas weren't horrible enough, this guy is a multi-lifebar ninja who often runs around the bridge you're on, making him a faraway target, and he has two ninja minions with him.
Star Fox 1 has one or two for each path. Path 1 features Phantron's One-Winged Angel form. Path 2 features Plasma Hydra. In Path 3, EVERY boss form Monarch Dodora on has the potential to be either this or a Breather Boss, and the Destructor and Blade Barrier can be this for new players.
Though in Path 3, THAT One Boss, the one everyone agrees on, is the Great Commander in the Venom Orbit. It has six extremely small hitboxes/turrets that must all be hit and slowly uses stronger attacks as you destroy more of the turrets. It'll get to the point where you have to risk Collision Damage to hit that last turret, and in this game, Collision Damage is a big deal. Multiple Lets Plays of the game will at least attempt to beat it fairly, but then use Game Genie codes to get unlimited Nova Bombs, which are the Great Commander's weakness.
In The Guardian Legend, Blue Optomon is definitely the toughest boss at the time you fight him. Absurdly powerful and long blue tentacles that are very hard to dodge, and you will go down in three hits or less no matter how much you're tried to powerup first, and you cannot gain recovery powerups during the fight at all. He takes forever to kill. And there is no secret trick to winning easily, unlike most other bosses.
Gradius III Arcade usually has easy bosses at the end of its Nintendo Hard levels, but not the bosses of stages 3 and 5. Stage 3's boss, Big Core Mk III, has much faster bouncing lasers than in the SNES version, and once its first two cores are destroyed, it starts spamming you with walls of Frickin' Laser Beams which you can just barely ease your ship through the gaps of. Stage 5's boss is six Moai heads, which are very hard to maneuver your options around to destroy, and addition spit out Mini-Moais that float around inflate as they are shot until they explode, restricting your maneuvering space. In other words, a boss that has nearly impossible to hit weak points and attacks by spawningDemonic Spiders.
Gradius V has a return appearance of Beacon, a boss from Gradius III SNES, as a Mini-Boss, but in this case it happens to be That One Mini-Boss, said by some to be the hardest enemy in the game(the Keeper's Core or Gun Wall midboss is considered by others to be harder) It now spams randomly directed bouncing blue laser beams, in addition to having a containment laser like Big Core MkIII, and on higher difficulties it has two sets of containment lasers, making it nigh-impossible to dodge the blue bouncing beams, unless you know a certain trick. It also fires bullet spams and drops fire bombs, in addition to the tunnel narrowing at points.
Gradius Gaiden has the last boss of loop 2 stage 8, Heaven's Gate, who will give you trouble if you're planning on a 2-loop clear. Lots of tightly-packed Beam Spam, a containment laser attack that it activates during one of its rounds of lasers to throw you off, and it fires suicide bullets upon its defeat.
Any gunwall in the series except for Gradius II's (Which has a rather pathetic safespot). Salamander/Lifeforce's gunwall spams indestructible cores that bounce about the area and are hard to dodge, and Gradius III's gunwall spams large amounts of enemies and bullets at you, plus the arcade version is equipped with Smashing Hallway Traps of Doom. Thankfully, most ports of Salamander and the SNES port of Gradius III tone down the gunwalls.
Solar Striker starts off as a pretty easy shooter until you get to the fourth boss, which is probably the closest the Game Boy has ever gotten to Bullet Hell. Be prepared to dodge like crazy as it constantly fires out of the sixteen turrets that surround it (half of them are uncomfortably close to you). There is a safe spot◊, but you're dead if you're even one pixel off.
In Einhänder, almost every boss can be That One Boss if you don't know what you're doing, but even experienced players have trouble with Schwarzgeist and Hyperion. The first loves Beam Spam and Macross Missile Massacre (though you can destroy the missile spawners) and has a small, hard-to-hit weak point. The second has a small weakpoint, spawns LOADS of Attack Drones and Homing Projectiles, and if you run out of time when fighting it, it instakills you in an unavoidable huge laser.
Battle Garegga's penultimate boss, Black Heart Mark II. Harder and denser patterns than the last boss and a small hittable area unless you're using a certain shipthat fires broadswords. It's only fitting that the best scoring trick in the game involves jacking up its aggressiveness and health to insane levels and dumping nearly all your remaining lives and bombs on it.
Raiden Fighters Jet's penultimate boss, a large Hover Tank, is a prime example of this sort of boss in a non-danmaku game that uses only bullets for enemy attacks. Every form has absurd amounts of health, it has an attack that leaves very slow bullets on the screen to trap you, and it spews undodgeable (unless you choose a certain tiny ship) attacks should you destroy forms at the wrong time. Did we also mention that if you lose all your lives and use a continue here, you get the Downer Ending?
Sin and Punishment's Birth Model. A gross name for a gross enemy. It's basically an enormous pile of eggs, which can shoot at you. Specifically, every individual egg can shoot at you. Good luck!
The final boss, which has you defending the ENTIRE Earth from an imitation Earth, which shoots a truly obscene amount of projectiles that you have to shoot right back at it. Fortunately, you're pretty much guaranteed unlimited continues for this fight, since said obscene amount of projectiles are the perfect opportunity to rack up gigantic combos, combined with the fact that said combos will never break, as the projectiles hit the Earth instead of you.
In some versions of Parodius Da!, stage nine (the zombie level) has a mid-boss that IS impossible without powerups. The boss is a series of umbrellas that circle the screen once, before homing it on you. The health they have makes an unpowered shot kill each enemy closer to you than the previous one was, up until one gets you. In the arcade version of the game, there is a space you can use in the bottom-right corner of the screen.
That boss is based off of Gradius 3's stage 3 mid-boss. And since the boss after that is That One Boss (At least in the arcade verson), if you get killed by that boss (And you will) you have to fight the mid boss again, and since THAT boss is That One Boss without powerups you have to face TWO That One Bosses in a row.
Star Fox 64: Macbeth, the planet in which is a Shout-Out to the title character of a William Shakespeare play. Perhaps the only time it has ever actually been easier to complete the special mission to go on the more difficult route (by shooting the eight switches to reroute the train into the weapons factory) than to not complete the special mission (forcing you to fight this ridiculous boss). Once you know where all of the switches are, this becomes easy, but if you miss one, prepare for a really challenging boss fight.
Said boss fight also comes slapped in with a nice time limit on it... that doesn't display. Take too long and the guy in the train says "It's time to finish this!" and then smacks the boss into you for an instant kill.
Sarumarine, the boss of Zoness kind of counts, too. A boss that actually forces you to use bombs. But carefully, because you don't really want to blow one of the cannon pontoons off while the exhaust pipes are still there. Oh, and if you're low on power (or playing on Expert, where your wings break at the slightest impact), remember to dodge to the side of the screen at the end, or else you'll get hit by the shrapnel from dealing the final blow.
The 3DS remake has far "better" detection for what qualifies as a proper hit, resulting in Smart Bombs being nerfed. Smaller blast radius means that Sarumarine goes from "kind of counts" to "the toughest, or at least most tedious, in the game."
The Bolse core, too. You wouldn't think destroying a satellite would be annoying, would you? It starts shooting back. Add to that the fact that the core rotates, and near the end, you could end up approaching the core only to find that the remaining targets are on the far side and you're getting nothing but a face full of lasers. Also, Star Wolf shows up on this level if you either didn't beat them all on Fortuna or came from a different route. Yay...
Resident Evil: The Darkside Chronicles has William Birkin, who wasn't exactly easy to beat in the original games. The second last chapter of the "Memory of a Lost City" stages has you first fighting your way through a level crawling with Giant Moths, Evolved Lickers, and Ivies, the latter two usually coming in packs of 2 or 3, and then facing off against Birkin — not just in his second form, oh no, you're gonna fight forms 2, 3 and 4! And did I mention that this is a sequential fight? As in, you need to face down each form, one after the other, in a single battle? The one mercy is that there's a checkpoint engaged between forms 3 and 4, which doesn't do you much good if you've already run out of ammo for your better guns on forms 2 and 3. The next level has Combat Mode Mr. X and then Birkin 5. Good luck.
You will come to hate Alexia Ashford, for more reasons than one. Her first form is easy, but once she evolves, prepare for hell. If her throwing fireballs that need to be shot out of the air isn't enough of a chore, how about tentacles that won't go the fuck away! Oh, she's easy because she's stationary, huh? Well, say hello to form 3; now she can fly, and unless you go through the button prompts, you can't get high enough to use the Linear Launcher without missing her constantly. And did I mention that you need the Linear Launcher to land the final blow on both forms 2 and 3?
Resident Evil: The Umbrella Chronicles has the Ivans: twin T-103 Tyrants clad in protective kevlar coats that leave only their heads exposed. You have to shoot them in the head, which becomes exponentially harder with the two of them double-teaming you. Worse yet, the game's most accurate weapons don't do enough damage to really make a difference, while the powerful shotguns and rapid-fire SMGs aren't accurate enough to hit the target consistently. To top it all off, dodging is nearly impossible; to stop them from hitting you, you have to shoot them in the head. Fun, huh?
Sigma Star Saga features the Chapter 5 boss, The Ghost of Iot. Although touching him will not damage you (unlike every other enemy in the game... he is a ghost after all), he has a very small hitbox, tons of health, and his attacks come at you from the background. From. The. Background. The most frustrating part is that he knows how to lead his shots, meaning that you have to be constantly weaving around in bizarre patterns to avoid getting killed. The only mercy in this fight is that, unlike most shmups, you are not a One-Hit-Point Wonder, and can take a few hits before dying.
Cobra is the bane of Silent Scope players. In one path in the first game, he runs around a stadium with the president's daughter on his shoulder. Failing to defeat cobra herenote Cobra escapes after a while, forcing you to pursue him down the highway will cause the other encounter to occur, in which he is riding in a constantly-weaving car using the president's daughter as a Human Shield, and throwing grenades at you, after which he hijacks a semi and tries to ram you, here you only have a small window to get a headshotnote or an extremely well-timed body shot before you lose a life. In the second game, he is on a grounded plane swaying back and forth, hiding behind a hanging hostage, and in addition to scrap metal and grenades, throwing hostages at you; the only way to avoid damage here is to get a precise hit while he's picking them up.
Descent: The original version of the 6-degrees-of-freedom first-person shooter has one of these bosses. The Level 7 boss is in the Shareware version of the game, too, which was always available to download for free. This guy is freakishly hard to beat, even by level 7 which requires a great deal of skill development to get to in the first place. By this time you don't have any really powerful weapons - the best you have are homing missiles (the 2nd weakest secondary weapon) and level 4 dual lasers (powerful, but slow moving, primary weapons). He, on the other hand, has rapid-fire smart missiles which are super-fast homers AND launch homing plasma charges upon impact with an inert object. He also happens to have the ability to teleport when he's in danger, and does so every time you hit him with something. You end up flying around, trying to dodge in and out of the caves in the middle, like a madman. Or cowering and hiding until he randomly teleports to you, firing, and ducking back in to a safe area. Ugh.
This is more of a Wake Up Boss. Not that you'll fight many more bosses like him (only one more in the full version in the final level) but a relatively simple tactic renders this boss an easy victory every time. The secret? You can fly as fast as homing missiles do. Just keep flying and you can't be hit.
The zero-gravity level in Air Buster / Aero Blasters has a nasty Mini-Boss that has halted many games due to the difficulty of dodging its attacks with the floaty controls.
Raiden IV's third boss. Three phases, the first two of which are already quite difficult, then it Turns Red and all Bullet Hell breaks loose.
The second boss is unpredictable until after you've fought it a few times, and is sure to get off a few cheap kills. In addition, its shots are fast and it rarely exposes its weak point.
The fourth boss pops in from the top of the screen and spews a ridiculous shower of lasers downwards, which is much faster than most of the weapons in the game and is very likely to hit you at least once even if you know it's coming. In addition, it moves in a pattern that will pretty much crush you if you don't have enough speed ups.
The sixth boss has two forms, and switching to its second form launches a shower of debris that's incredibly difficult to deal with. In addition, it has a pair of arms which make it extremely difficult to maneuver. The worst part? The best weapon to destroy them with is the defensive fire, but if you end up in front of the it only way to stay alive is to be in offensive mode (where you can actually move). Add on a difficult stage and you have a really nasty foe.
Super Spy Hunter features the boss of level 4: A long level that features a single narrow road, with patches of frictionless glass and long jumps that are easy to miss in less than 30 second intervals. They throw a boss, which is a moderate size cube only two vilnerable spots, which are two lasers that can one-shot your car even with full health. Once you destroy the lasers, it chases you aggressively, continuously shoots its spread shot at you and can only be hit from exactly straight ahead or behind. Any little deflection of angle and your shots harmlessly impact his invincible spots.
Heavy Weapon has the Final Boss ("Secret Weapon"). This thing has three phases. The first phase shoots out lasers from its sides that either go straight down, diagonally, or curve around. Touch any of those and you're dead regardless of shields. The second phase has it spray purple shots while it periodically drops an A-bomb. If that even touches the ground before you shoot it down, you're also toast! The third phase is a Macross Missile Massacre that is the easiest of the three, you can shoot the missiles down and he cannot give you a dreaded One-Hit Kill. Did I also mention that when you die, you lose ALL your Smart Bombs which would have made the boss easier? Also, he comes at the end of a hard and extremely long level filled with Demonic Spiders.
Space Invaders Extreme 2 featured a branching path system, but only five bosses, though each boss got tougher on a harder path. The Final Boss of the hardest path is RIDICULOUS, becoming the Space Invaders equivalent of Bullet Hell. The final boss is the final boss from the first game, but MUCH larger. The boss has five different phases. The first is a long introductory attack, firing diagonal angling shots and bombs with a blast radius that can also stick onto the floor. The second and third phases alternate afterwards. Here is where you have to start attacking the weak points, which have a TON of health. The second phase is the first attack it used in the first game, but fires even quicker and for a longer period. The third phase spawns giant Mooks with a TON of health. Said Mooks spawn the game's Goddamned Bats to help them out: the enemies with Deflector Shields, which is a pretty good defense. Oh, and while this happings, the boss and Mooks are firing. Once you beat the first two weak points, the final weak point will arrive and the fourth phase will start. the boss will summon a much smaller version of itself that fires shots that take up quite a bit of your movable area at a time while the main boss fires the angling shots that deflect off of the sides of the screen and the bombs. Once you destroy the small one, the final boss will Turn Red and go COMPLETELY berserk, firing a UFO that leaves behind energy balls that splits into three shots and lasers. While this is going on, you also have to fire at the weak point while doing so. Upon FINALLY defeating it, you can relax... but know that if you lose your all of your lives, you start over at the introductory attack if you're playing the main mode. If you select the level to play by itself, you have to do the whole level over. Have fun.
Hellsinker has the Segment 6 bosses, the Apostles of the Seed, quite possibly the hardest non-final, non-bonus bosses in the game. Their opener consists of one of them firing bullet spreads at you while the other shoots Homing Lasers, forcing you to move precisely and quickly at the same time. Once this phase is over, the next part consists of various attack patterns that are in a pseudo-random order. One exceptionally deadly attack has one of the Apostles fire a spread at you and a Wave Motion Gun at the same time, another boxes you in with beams while it fires bullets at you. Sometimes you may get unlucky and one attack leaves you pinned and unable to dodge the next attack! The duo also have a Combination attack in which they spin around the screen rapidly connected by a beam, while spewing out various attacks at you, some of which knock you around rather than trying to kill you outright. Also, killing one of them causes the other to go berserk with an extremely hard attack. And finally, once you do kill the bosses, the stage continues and is harder than ever!
RefleX's Area 7 boss and Area 8 bosses don't have particularly fierce attacks compared to the rest of the game's, but what makes them stand out is that while the rest of the game allows you 6 hits and refills your health twice along the way, these two boss battles have NO room for error due to storyline events that give you boosted firepower and an infinite shield at the cost of all spare armor. You must complete the last bosses without getting hit AT ALL; if a single missile reaches you (you can shoot missiles but you can't shield against them) or your shield isn't up when a bullet hits you, GAME OVER.