Zelda II: The Adventure of Link, having a much different playing style than the other Zelda games, can seem full of demonic spiders to players who haven't got the hang of the mechanics yet. And even then, some border on this. For example, blue Lizalfos, which in this game 1) use a shield that blocks most of Link's attacks, and 2) throw hammers that his shield can't block without the reflect spell. But the champion of Zelda 2 demonic spiders would be the appropriately-named Fokka, otherwise known as the Bird Knights in the Great Palace. Like Iron Knuckles and Lizalfos, they have a shield and shooting sword. They also take huge leaps with no warning, which causes them to kick Link in the head. Oh, and with Link's defense power at maximum, they take off 1 and 3/4th of a block of life, out of (up to) 8 total. Oh, and where the aforementioned Blue Lizalfos was worth 200 experience points? Bird Knights are inexplicably worth only 70 (red) and 100 (blue).
Blue Wizzrobes from the first game. By the time you get the Magical Sword, orange Wizzrobes (and most other foes) cease to be a threat, getting cleaved in two in a single swing, but the blue Wizzrobes (unlike the orange ones) are ALWAYS in motion, take three swings to kill, if you run in front of one they blast you with a beam that'll take a whole heart even with the max Level 3 armor ring and, as described in the page on Goddamned Bats, love to hang out with Bubbles, which take away your ability to swing your sword, and Like Likes, which eat your magic shield, which can block Wizzrobe projectiles. Like the Darknuts mentioned below, they're impervious to everything except your sword and bombs. You see a blue Wizzrobe, you do what we do. You run your ass off. Unless the next room is sealed and you're forced to fight them. Which, of course, it ALWAYS IS.
The one-hit killer Phantoms and the Phantom Eyes that warn them in Phantom Hourglass. The fact that you have to return to their dungeon SEVERAL TIMES in the game really gets frustrating; they get harder to avoid as you progress, eventually teleporting around the place and you can't get rid of them until finding the right sword. When you finally do, its very satisfying to kill them.
Better yet, both the Phantoms and Phantom Eyes make a return in Spirit Tracks, and this time there's no Phantom Sword to kill them. Luckily, you get to do something almost as satisfying. Also luckily, unlike the Dark Trains listed further down, "one hit kill" doesn't mean "instant Game Over", so much as it means "get forced back to the beginning", Wallmaster style.
They get a Spiritual Successor in Skyward Sword, the Guardians of the Silent Realm. First off, the only Safe Zone is the entrance - once you're out, the Guardians are on you like white on rice. Secondly, a single hit banishes you and dismisses your Tears of Light, forcing you to start over. Thirdly, your entire inventory is banished from your person, so no Stamina Potions or shields for you. Finally, even if you collect a Tear of Light, the Guardians are stilled for a minute and a half or until a sentry spots you. Thankfully, you retain the map marks for every Tear you collect before you're banished, so if it happens you don't have to start from absolute scratch. Good luck - you'll need it!
Darknuts: You can only hit them on one side which is practically impossible when they're walking around in such randomly erratic directions. You think you're about to get a good hit in, but then CLANK! You could have full hearts and still manage to die because of a single idiot Darknut encounter. And if you didn't think it could get any more ridiculous, in every dungeon there's like 50 rooms FULL OF THEM and all it makes you want to do is turn the game off. Worse than the Wizzrobes... maybe... yes.
Case in point: In the 5th labyrinth, you have to go through 2 rooms to get the whistle, full of nothing. But. Blue. Darknuts. Odds are if this is your first playthrough you have only the white sword, which, if memory serves, requires you to hit them 4 times (though it's possible to have the magic sword, reducing that to 2 hits). And the blue ones are smarter than the red ones and thus more likely to position their not-squishy side in front of you... make it stop! MAKE IT STOP!!!!
They're such Demonic Spiders that the designers of Zelda Classic went so far as to make it possible to set up your own custom quests such that the hammer can be used to break their shields.
Too bad you'll be needing that to even the playing field against the even harder Darknut variants added. The Super Darknut moves just as fast as Link and can take 4 hits from the Magical Sword...before splitting into two Blue Darknuts. But worst of all...the Death Knight...who moves faster than Link, shoots sword beams, and deals 20 hearts of damage (more than the maximum health of the original Zelda game). Unless the quest sets up the level with safe places to use the Ladder (which it often does), you are DEAD.
They were drastically nerfed in The Legend of Zelda: The Wind Waker. The Legend of Zelda: Twilight Princess knocks them back up a little but not too bad, until the Bonus Dungeon where three of them walk in this tightly-huddled group that doesn't allow you to attack all of them. And if you try to attack one? The OTHERS strike you. Doesn't help that the Twilight Princess ones are still menacing when their armor's off.
Don't forget the extra one under the entrance platform on the second playthrough.
Yeah, the ones in Minish Cap are easy to beat with remote bombs. Just set down a bomb, let it run towards you, set off bomb, and it's stunned. Slap around as you please.
There's also the Darknut Expy, Ironknuckle, in Adventure of Link. They carry shields like their cousins, and they force you to play a guessing game of striking high or low to damage them while they swing their swords right back at you. The orange and red ones get easier once you get stronger (and you realize that striking them while jumping at them can bypass the shield), but the blue ones are what truly belong on this list. They're fast, powerful, they spam Sword Beams, and they have a nasty habit of backing away from you when you get close. Lizalfos, of which the strongest variant is mentioned above, behave similarly to Ironknuckles but manage to be even more annoying, as do the appropriately named Fokka, also mentioned above.
But they're much more menacing at small size, after the big ones separate. When grabbing you they take out several hearts and stopping them from grabbing you is nigh impossible. If all three latch onto you you are dead, plain and simple. The full-size ones' strikes aren't nearly as bad. Oh, and they become full size after a while, requiring you to hit them again and brave even more of the miserable beasts. Three are nasty. Six are insane. Nine... there hasn't been a final boss as bad as nine of those things.
The Legend of Zelda: Spirit Tracks has the evil Dark Trains, along with their smarter, tougher cousins the Armoured Trains. Heaven help you if you find one in your path, because if it moves towards you, you better be near the last fork and it better not follow you or you're on a one-way train ride to an automatic Game Over. Just to make it worse, the Aumoured Trains pursue you until you leave the area. Even getting to a fork backward, quickly shoving the train in reverse and flipping the switch will only get you a few seconds' respite. To make matters worse, they are often found right in front of a station or area that you need to get to.
The Legend of Zelda: Skyward Sword manages to escalate Skultullas (bonus points for them being literal spiders) from mere cannon fodder into this. Players of the preveous games should know to aim for their soft underbelly, but will soon find thatthey'll no longersimply present their back to you. Instead, you have to slash them with your sword to make them start swinging, but you have to get the angle right, do it wrong and they'll be swinging right at you. But you're not done yet, you now have to hit their belly with the Slingshot to stun them. Hitting a rapidly moving target is a lot harder than it sounds. And you're still not done, you have to finish the job with your sword, but only one type of strike will work. Specifically, the forward stab, which the WiiMotion Plus is notoriously unresponsive to. Do any other type of attack, and you'll flip them back and START THE ENTIRE PROCESS OVER AGAIN!!! Of course, their much easier once you've figured out this process, but they're the first enemy that requires such a complex sequence of steps to defeat, and they will kill you if you get it wrong.
Alternately, once you have it, you can use the Beetle to sever their threads and force them to the ground, but they will try to wrap you up in thread and nom your face off. Offensively they're less threatening, but defensively they're still a pain - this time you have to front flip them to expose their underbellies and deliver a Fatal Blow. Pick your poison.
Said flipping can be done with a single upward slash at literally any moment they're on the ground. It makes killing them pathetically easy (a single slash followed by a Fatal Blow), so chalk this one up to players refusing to experiment and the game's total lack of advice on it.
The formerly manageable Lizalfos were elevated to this status in Skyward Sword. Rather than relying on dodging like in Ocarina or having only rudimentary blocking abilities (as in Twilight Princess), they now have enormous iron gauntlets that can not only block most sword attacks, but will also render ALL ranged attacks useless unless you manage to catch them unawares from behind; you are pretty much forced to take them in close quarters. And then once you do so, prepare to have them either jump away from your sword at the last second or block you with the aforementioned gauntlets. All while occasionally stopping to taunt you with the most annoying noise imaginable (though thankfully, they become vulnerable at this point). A single Lizalfos is usually not too tough, but they tend to attack in pairs, and unlike in past games, they don't practise Mook Chivalry, and will not hesitate to gang up on you. Also, they now have fire breath which lets them attack from a longer range than they could in previous games.
And of course, it gets worse with the Escort Mission late in the game, wherein Scrapper will, as usual, get suicidally close to you as you attempt to strike these fiends down.
And later still, they gain cursed breath which completely disables all of your weapons. No sword, no, shield, nothing at all- you're completely defenseless until the curse wears off, which takes a long time.
And, frequently found in the same area, the Skyward Sword incarnation of Armos, which requires the player to walk around pointing a leaf blower at a propeller on the monster's head (without the benefit of Z targeting) while it flings itself at you, and then, you guessed it, forward stab a tiny guarded spot before they make their swift recovery.
Anything in Minish Cap with fire attacks is a pain, since a fire wound inflicted will induce you to run around screaming rather than being controllable.
This applies to the GBA/DSi Four swords. Except with damage, and trying to retain the effect of double Rupees.
Let's talk about Redeads, in any of the games they appear in. Though not too difficult once you've landed a hit, their ability to let out a horrible scream that paralyses you can often make doing this practically impossible, especially if they gang up on you. It may reach a point where you cannot move at all as they come closer, which depending on the game, either means you will be hacked to pieces by a zombie skeleton or disturbingly humped to death. These guys have trauma potential.
Lynels in the original game, The Legend of Zelda: A Link to the Past and The Legend of Zelda: A Link Between Worlds. Centaur like things found on Death Mountain in both games, they not only have a fair amount of health, but do a ridiculous amount of damage with their attacks. How much? Well in the 3DS game, enough to kill Link in one hit if before about the fourth or fifth dungeon, especially in Hero Mode. And they have projectile attacks in the form of beams (older games) or fire breath (A Link Between Worlds) which can only be blocked with the strongest shield in the game. Did I mention that you tend to fight these things in narrow passageways on top of mountains with little room to dodge? Or that in the 3DS game, you have to sneak past two at the same time in at least two different areas to progress?