The original Diablo had the undead mages at the end of the game. They came in swarms, had lightning attacks which could shred your HP down to critical in a few seconds, and teleported away from you before you could do any significant damage. The bane of warriors. It's not unknown to run out of money to spend on healing potions before you run out of enemies to kill.
And if they weren't bad enough, they'd often be accompanied by Soul Burners. These winged demonic harlots would NEVER be encountered on their own, and while they weren't able to teleport around like the mages, approaching even an average-sized cluster of them with melee in mind still bordered on suicide for anyone not tooled-up to the eyeballs with special items and healing consumables.
Diablo II is the quintessential example of this trope. If the game did not pre-date TV Tropes by several years, one could be tempted to believe its programmers used the article as a checklist for creating annoying enemies. To make the game more difficult, nearly every method of unfair fighting is used, including sudden charges forward, death explosions, attacks from off-screen, and worst of all, hitting the player with lightning every time the player hits a certain foe.
The infamous "Scarab Demon" enemy type, which shoots lightning in all directions every time you hit them. Also known as "that fucking bug that shoots fucking lightning in all directions every fucking time you hit one." The same thing also go for when an enemy is "Lightning Enchanted." A further refinement yet is the dreaded "Multiple Shot Lightning-Enchanted," (MSLE) which multiplies the number of lightning bolts released on hits to such a degree that one wad can kill most avatars; also, the engine's limits sometimes fail to display all the clustered bolts, leading to possible surprise death, even at a distance.
A note on MSLE: MSLE increases the number of sparks generated on every hit, but also causes those sparks to home in on you. A standard LE boss can easily be cheesed by standing about half a unit away in any of the four cardinal directions (Directly east/west or north/south) and whacking away at it in melee. With an MSLE mob that just ain't gonna happen. Zap.
Thankfully, MSLE bosses have been fixed as of 1.10. They still emit lightning and still use multiples of their normal projectiles, but the two enchantments no longer work together.
King of the Demonic Spiders would have to be the gloams/souls (Gloams, Burning Souls, Black Souls) that show up in acts 3, 4, and 5. (So hated that they were listed here in three separate places...) They shoot lightning, at range sufficient to hit you a screen and a half away, which deals insane damage. And they're invisible most of the time. Very often your first warning of a pack of gloams is when a volley of lightning bolts from something you can't even see hits you in the face and wipes out three-quarters of your hit points.
And that's even when you have max lightning resistances sometimes!
They are also unleechable. Have you been relying on leeching mana from monsters to power your attack skills? Whoops! Gloams won't give you any mana! Leeching life to keep from dying? Can't get that either! Sucks to be you.
The Tomb Vipers as a guest monster in Act V. Their ranged poison attack leaves behind an invisible trail that, if you try to run through them, will inflict half physical half poison damage PER FRAME (the game runs on 25FPS), often instantly killing the strongest characters unless you load up on integer physical damage reduction. This has frequently been requested as a bug fix but blizzard insists that it is "working as intended". Thankfully they are only found in one place. (Tip: if you see those things and don't want to save/exit/reenter for whatever reason, STAND STILL. Also don't count on any of your minions as they're likely to run through the clouds and get killed instantly unless they're dual poison/physical immune revives or Druid's spirit summons in Nightmare.)
The Claw Vipers don't seem that fast, but if they get within a few feet of you, they can cover the remaining distance at roughly twice the remaining speed, hitting you and stunning you with their charge attack. It's almost impossible for a non-melee class to get the amulet from the second level of the temple alone.
They not only stun you, they knock you backwards. Running into a large group of them can make you feel like a pinball.
The highest ranking variants of the Reanimated Horde are naturally Extra Fast-er than the rest, and their deadlier and more frequent charge attacks give the Claw Vipers a run for their money. Since their type can self-revive, players back tracking through an area previously riddled with this sort of undead may be in for a painful surprise.
Archer groups with Cold Enchantment. One hit freezes you, so that you can't get to them quickly, and they're shooting at you the whole time. They're especially hell on melee classes, since melee attacks are also slowed to a crawl when you're frozeen. One of these groups spawns in act 1, every time without fail. They will wreck your low-level characters and absolutely ruin your day.
Archer bosspacks in general can do quite a lot of damage from range in Hell, especially if they're loaded up with nasty mods. If you encounter them with melee classes to tank for them, you should probably retreat so you can take out any distractions first.
Undead flayers. They're tiny little skeletons that run around with giant cleavers as big as they are. They run up to you at super-speed, stab you in the face for a bunch of damage, and zip away. They're so small and fast-moving that it's very tough to click on them. Missed... aagh... missed again... HA! Gotcha, you little motherf—KABOOM! (Oh, did I mention they explode when they die? And the explosion damage is enough to kill many characters outright?) Luckily their explosions don't work on mercs and minions for some reason, so you should let yours do the dirty work for you.
Until recently, oblivion knights were the absolute bane of melee characters. They're undead casters in the last bit of Act 4 and sometimes Act 5, who throw random curses at you. Every so often they'd throw Iron Maiden, which causes you to damage yourself every time you make a melee attack. If, God forbid, you're in the middle of a high-damaging, long-animation attack such as Zeal or Whirlwind, it's an insta-kill. In fact, damage scales faster than HP in D2, so on higher difficulties Iron Maiden is an insta-kill if you land any melee attack. The 1.13 patch removed Iron Maiden from their list of curses, and they've since been retired from Demonic Spiders status. They can still make you die quicker though, if they cast Lower Resist while being next to the aforementioned Gloams.
Similar to Oblivion Knights, Unique Fallen Shamans were absolute nightmares before later patches toned them down. See, the main shtick of Fallen Shamans is that they can resurrect the Fallen of their "tribe". Now, Unique Shamans also had the ability to resurrect other Shamans, and they had minions that could do the same, making any encounter with them a mad dash to kill them quickly and pray to Akarat they don't spam their resurrections. Mercifully, later patches eventually both removed their ability to resurrect other Shamans, as well as giving them standard Fallen as minions.
In Act 5 Nightmare and Hell, the Cold variants get Glacial Spike. Sucks for mercenaries that get too close.
Fetish Shamans. They pace about faster than Fallen Shamans, and instead of a puny fire ball type attack they use the most damaging fire attack encountered so far in regular monsters possibly until Act 4: Inferno. With all of a shaman-type monster's benefits. Oh, and they also have their own fetish to attack you after they're killed. AND they take on the class of the shaman in question ie. Unique shaman, unique leftover fetish with the same mods.
Act 5 Wendigoes. Beefed up fundamentally, now also with the ability to stun. Champion packs of these exemplify this trope.
The Yetis sort of look tamer once you run into Minotaur packs. Especially a unique pack with nasty mods(Fanaticism AND Extra Strong AND Extra Fast on top of their Frenzy, anyone?) that spawned on top of you because you clicked on that evil urn hoping to get an easy-to-handle succubus pack to score on EXP and loot.
In the original, and also in the sequel's expansion: Monsters that attack using Blood Star. Due to the game's dearth in providing substantial defense towards the generic "MAGIC"-type damage (ie Bone Spear, Berserk, Blessed Hammer etc) for players, a frequently-encountered stream of blood stars will cause immense grief to characters that don't explicitly load up on hit points and the mod "Magic Damage reduced by [integer]".
Hell Bovines are these to casual players. If a 1280x1024 or higher playing resolution was available, once you step through the portal you'd find yourself almost totally surrounded by bovine packs.
You know this game RUBS this trope in with those suicide minions in Act 5.
Diablo III continues the Demonic Spider tradition with the various elite packs you will encounter on higher difficulties. Many of the monster traits these elites come with aren't too bad on their own, but in the higher difficulties, elites and their minions can have two (on Nightmare) to four (on Inferno) of these traits at once, and they will use them to their fullest extent to ruin your day, at times being even tougher to kill than end-of-act bosses if they get a particularly nasty combination of powers. To name just a few:
Arcane Enchanted enemies, which first appear on Nightmare. These guys love to lay down these purple laser things reminiscent of those fire stick things from Super Mario Bros.. And they hurt if you get hit by it or if one spawns right under you when you can't get away (say, when you're locked down by a Jailer).
Jailers combined with any attack that does high damage over time, like a Desecration pool or a Blazing Guardian's fireball.
Shielding enemies are just a royal pain in the ass in general, but when combined with other fuck-you-worthy powers, they can really ruin your day.
If a champion/boss-level monster has Invulnerable Minions, you will hate that boss. Especially in the later difficulties.
Blizzard removed these enemies precisely because of this, and also because of a bug that would result in them being kept around with their full invulnerability after the boss that spawned them fell.
Mortar enemies can rain unholy hell down on you (which is very problematic if you're a ranged class), though they have a minimum range.
Molten enemies leave damaging pools of lava in their wake, making melee problematic at best, and explode upon death if they're not a minion.
Fire Chains enemies are connected by a fire chain that does nasty damage if you're caught between them. And these enemies often have another quality with them as they only spawn on Nightmare or higher.
Health Link elites are particularly annoying to deal with, as they share a single, hard to bring down life bar between them.
Vortex elites can yank you right into melee range, which can be aggravating if you're trying to keep away from them.
Desecrators create a glowing void zone that does damage to anyone near them, and is a particular problem for melee characters.
If an enemy mob has the Reflects Damage ability, you are not going to like being in melee with it. Full stop.
Apart from champion packs, there's also the Desert Wasps from Act II. At a point where most enemies will be doing single digit damage, their ranged attacks will be doing several times that damage, and can hit multiple times since they fire multiple shots at once. Plus they are quick, retreat, fly over terrain, and fire at you. And never attack alone.
Between unblockable attacks, offscreen projectiles, lack of Mook Chivalry and various other factors, almost all the enemies from the Xbox remake of Ninja Gaiden count.
One of the worst types of enemies is the brown ninja that throws exploding kunai at you—not only are they unblockable, but they explode and knock you down seconds later, often in mid-combo, and do quite a bit of damage. Ironically, the Cat Fiends, which replace the ninja in Tairon on Head Ninja mode, are easier.
The ninja dogs in the second game are an arguably even more painful version of this. They come in packs of six or more, strike so quickly it's hard to see them coming, use exploding kunai at higher levels, and you can't hack their limbs off so obliteration techniques don't work. You just have to slug it out with them.
The Ghost Fish are worse. They're small, numerous, impossible to block (since their move is considered a throw) and if there's at least two of them (they come in groups of about 20) it's entirely possible that if they hit you once, you will be treated to a minute or two of watching them eat away at Ryu's health until he dies, all while the player is utterly helpless. The best way to deal with them is to use the nunchuks/Vigoorian Flail to smack them as they fly in to bite you, but even using the longest combo, it'll end long before the attack does, and they'll immediately exploit the opening you leave. It would probably not be so bad if they weren't everywhere in the last two or three levels.
Archers. They are the only thing preventing you from going on a rampage seated on your dragon, as a large enough group of them will skewer her alive. Later on, Undead fill this role. And then the Grotesqueries, which always come in groups of six for some reason.
At least crossbow bolts can be blocked. The mages will hurt you even if you are blocking. And guess what? They can snipe your dragon out of the sky, too! Freakin' beautiful!
There is a grim reaper-ish enemy in the second game, that only appears in later flight stages, but is ridiculously hard to kill. At long range it always seemed to block Legna's attacks (including the breath powerups) with its sickle, making it so you could only really damage it at point-blank range. Problem is that as soon as you get close to the enemy it will usually cleave about 1/3 to 1/2 of your dragon's hit points away. You only ever seemed to have a second to attack it and fly away before it attacks. They also tend to have a bunch of minor enemies swarming around them, messing with your targeting. I almost forgot to mention that they love to hurl their sickles at you.
Undead enemies in the sequel are still a pain in the butt, and on Extreme mode, every enemy is a demonic spider.
Enemy officers turn into Demonic Spiders if you've drawn aggro from more than two. They love to wait until you're attacking one of them, trying to break his block, and then they wail on you in sequence, knocking you from full health to a flashing red sliver. The only way out is to roll away from the mass of Mooks (if you're lucky to actually manage it before they kill you) and run away until you find a health item.
Riflemen in Samurai Warriors will piss you off to no end. You can walk through their shots on foot, but gods help you if you're mounted: a single shot sends you spinning through the air for forty feet.
Very early on in Bayonetta, you have to fight Grace and Glory, a pair of angels with matching fire and electric claws that can utterly curbstomp you if you make a mistake. If you've seen Agni and Rudra in Devil May Cry 3, you'll know the general idea with these two. They can juggle you after knocking you into the air or launch their claws like hookshots, they move very quickly, and they're about as predictable as mental patients (that is to say, not predictable in the least when you first fight them). One of them can send sparks along the ground, which will hit you if you're the least bit distracted, and the other can spin in a fiery tornado that's impossible to hit out of without Witch Time. Whenever you make one of them flinch, the other will be hot on your tail before you can dish out a combo unless you manage to juggle them in the air, or focus your efforts on killing one at a time instead of alternating between them. The worst part? They become degraded minibosses over the course of the game, so you end up having to fight something like six or seven more pairs of them, and during many of the later fights you can't get Witch Time by dodging their attacks. And just wait until you reach the highest difficulty level...
The golden copies of Grace and Glory, now named Gracious and Glorious, which have the same attacks as the normal ones, but seem to flinch less often, and are stronger and more aggressive—and to top it off, they never give you Witch Time when you dodge unless you use the Moon of Mahaa-Kaala to block their attacks, which requires crushingly precise timing. In Hard mode, you have to fight three of them at once.
Worse than Grace and Glory (but not as bad as Gracious and Glorious) are Fearless and Fairness. Both appear to be quadrupeds, one blue and one red, and their attacks not only do a lot of damage, but also come with next to no warning. And they have a move unique to each; Fearless has a scorpion-like tail stab that can hit at long range, and Fairness roars to stun you. If you don't break free, it will maul you. Fortunately, they're rarely fought simultaneously.
At Non Stop Infinity Climax, Fairness and Fearless turn into quite possibly THE worst enemy in the game. You know how it says above that Fairness and Fearless are between Grace/Glory and Gracious/Glorious in difficulty? Well, the only thing that normally makes Gracious and Glorious that much worse than any other enemy in the game, and particularly their weaker versions, is (besides increased vitality and resistance) the fact that you can't get Witch Time off on them without absurdly precise timing. Now, on Non Stop Infinity Climax, Witch Time is disabled completely. Have fun.
Who can forget Kinship with its homing missile swarms that are really hard to dodge and their laser attack that's rather hard to see coming if you're already focusing on one? Thankfully, they're even rarer than the above four enemies mentioned here, but they are never solo in the main game.
Abysses from Devil May Cry 3. They always come into trios and have an annoying attack where they sink into the ground and then leap out elsewhere throwing a powerful firecracker. This attack usually cannot be interrupted. In addition, they can throw the firecracker from offscreen with little indication. When they are knocked away, they backflip and dash forward to attack again, limiting your combat options. Sometimes they come with other Goddamned Bats too. In fact, on higher difficulties almost all Devil May Cry enemies can be Demonic Spiders. Feel free to elaborate on other examples, though.
The literalDemonic Spiders are VERY annoying: not only they attack with little warning (a standard manoeuvre in DMC universe), they like to block your hits and THEN dash at you bellowing, must be hit several times in a row before they start to back off (instead they attack in the middle of your combos), like to immobilize you with their webs while another is about to attack you (talk about Mook Chivalry) and to top it all they release exploding baby spiders when they finally meet their demise. I often try to finish them off with Agni & Rudra just for the satisfaction to see them split in half. Oh, and did I mention there are BIGGER VERSIONS of the same enemy?
Whoops, missed the Enigmas. These arrow-firing animated statues are difficult to combat with melee at higher difficulties because they can skitter away faster than Dante or Vergil's chasing moves. Their arrows can quickly make pincushions out of either character and can throw off Dante or Vergil's attacks even when the Devil TriggerSuper Mode is used. They flip the proverbial bird at the idea of Do Not Run with a Gun. Enigmas can be dissuaded from firing if knocked around by combos, but longer combo strings need to be used at higher difficulties and in Dante Must Die their own version of the Devil Trigger makes them nigh-impossible to knock around. Not to mention that trying to shoot them dead from offscreen is a lengthy process made longer by the extra endurance granted from the Devil Trigger. Yes, the arrows can be destroyed—but tough luck if you forgot to bring the optimal weapon as Dante, and Vergil's optimal method is not foolproof. Add on the fact that Dante's optimal choice is outranged by the Enigmas...
The Chimera-possessed Scarecrows of Devil May Cry 4 were just as sluggish as the usual scarecrows, rarely attacking and moving slowly, waiting to die. The catch? They always attack and interrupt, even while being attacked and interrupted. They were usually fighting like an average enemy, but so was the newly acquired parasite, who would swing its blade-like limbs at the player in any instance that he was near. They especially liked to do this while downed or sent flying, leaving combo-stringing and pursuit as an option virtually nonexistent. This meant that players had to rely on run-&-gun gameplay and constant ranged and blow-back attacks, then move on to the next one to keep the lot of them at bay. God forbid if they surround you. Then there's those Chimera-possessed assaults, who subvert the previous' mentioned sluggishness by being regularly tenacious. Oh, and they have more life than the regular host.
To add to your pain the Chimera-Scarecrows and Chimera-Assaults could attack you whilst they were being grabbed! Sure it was possible to disable the flowers for a few seconds, but it's not unheard of for them to recover mid grab, then flail at you, ruining your no damage run, opening you up for a nearby enemy (especially Chimera-Assaults) and on DMD, taking off a huge chunk of life even if nothing else decides to hit you.
Nobody should forget about the Faults of DMC4, ARGH!!! They appear out of nowhere and drag you to a different area much like Nightmare from DMC1. Difference is that when Nightmare did that it was cool and clearing out the area took out a large chunk off its health, Faults are plain annoying when you're trying to fight a horde of demons on Dante Must Die Mode. Mission 14 is the embodiment of how much you should hate Capcom because of the Faults, because in Mission 14, if you get caught by a Fault, you'll be transported to an area with Chimera Scarecrows, or sometimes even Chimera Assaults, themselves being bloody Demonic Spiders.
And who could forget the Blitz? Moreso when doing the Bloody Palace, since they were coupled with other enemies. Trying to keep Alto Angelos off your tail while there's an invisible enemy ready to jump you from literally any direction is vein-poppingly maddening.
DMC Devil May Cry starts out a bit mild compared to the previous DMC games, but in mission 7, you'll come across the aptly-named Rage. These cat-porcupine hybrid of doom have a nasty habit of dodging your grab attempts, have combos (whereas most other enemies usually will smack you once before preparing their next attack), and are rarely fought alone. And they also have elemental versions of them, meaning that out of your four types of weapon (sword, gun, angel weapon and demon weapon), only either of the last two can harm them depending on the color.
Then there's the Witch. She's covered with a shield which can only be broken with Angel weapons (other weapons will bounce off them), likes to teleport, and if you fight them with other enemies, the witch may decide to send her shield to the other enemy. Worse, the shield is opaque, so you can't quite tell what the shielded enemy is about to do to you. In harder difficulties, they'll throw THREE homing swords at once instead of normally one, and the enemies they are paired with are a lot worse.
Subverted with the Death knights, in his first battle one death knight only is relatively hard to beat, but when Dante gets arbiter, they become much easier to overcome, even one may defeating entire groups with relative ease.
Even the Lesser Stygians you've been slaughtering left and right in lower difficulty mode WILL become this in Dante Must Die. See, they gain the ability to block your attacks. No big deal you think? That blocking will force you to take more time dealing with them, and taking a long time is not advisable in DMD, where enemies will Devil Trigger after some time, making them all the harder to kill. The worst part? Thanks to their status as lesser mooks, Lesser Stygians have extremely short fuse for Devil Triggering; You don't finish them in a few seconds, they'll make your life HELL.
Prince of Persia: The Two Thrones: The hounds can drain your Sands, and don't yield any when defeated. They're especially deadly when a hard platforming section is up ahead.
In Prince of Persia: The Sands of Time, Bats could come at you when you were JUMPING FROM LADDERS TO SWINGING POLES several hundred feet above the ground, and if they are touching you for more then a second, you will fall to your death.
The puppy Cerberoi in the second God of War game. Very maneuverable and hard to hit. Take too long to kill them, and they evolve into full-grown Cerberus mini-bosses. (The Fuck-You Button is the most effective way to deal with them - not to mention the only way, at higher difficulties.)
Likewise the Satyrs, who don't evolve but are practically impossible to stagger, meaning you spend more time dodging their attacks than countering. If you grab them, it initiates a button-mashing grapple for the satyr's staff, which would be well and good except there's usually two of them per fight, and they show blatant disregard for the rules of Mook Chivalry.
There are several of these in the PSP version - or perhaps they just get introduced into gameplay more quickly. The worst ones are guys who are Dual Wielding: you can't block their attacks, they have five-second-long combos, and they always come in packs. So: Dodge, dodge, dodge, dodge, dodge, dodge, land one hit, Lather Rinse Repeat. (Actually, if you're quick, you can stagger them out of their attack patterns, but if you miss that first dodge, it's them juggling you.)
The Goddamn Satyrs and Wraiths in III.
Not so much the Wraiths once you know how to rip them out of the ground like Saddam out of a spider hole.
Sirens in Chains of Olympus, who have picked up the mannerisms of aformentioned wraiths, sink into the ground when they land after a knockback, and leap out of the ground to put you into an action sequence, this wouldn't be too annoying on its own, except the lunge is ridiculously fast, tracks you, and is one of two attacks in the game (the other belonging to armored cyclops) that can knock you out of your block + attack invincibility frames, did I mention there's a part where you have to fight three of them and an armored cyclops at once? Good luck getting an attack in before you have to mash L and R.
Hopefully you'll be sufficiently powered up before you encounter the Heretics in Dante's Inferno. They only appear in the second half of the game (particularly in the City of Dis), but they're durable, can teleport, usually appear with a Mook squadron and make everyone else impervious to your attacks until the Heretic dies, they'll hit you with a bola-like spinning thing if you're too close when they're lying down...but the real kicker is that they can make ANY other enemy invincible if they appear in the same wave, including enemies who already border on Demonic Spider territory in their own right.
The Heretical Priests. They have the nasty habit of rendering themselves and anyone around them cross-proof (but not magic-proof!) until the Priest dies. On their own, they can be handled relatively easily, but they get really annoying when they use their protection on angered spirits, shades that catch fire and can only be attacked by using the cross attack (or holy magic) to put out the flame.
No More Heroes as a series will make you despise any enemy who uses a gun. Blocking the bullets eat away at your sword meter fast, and they usually appear behind incredibly strong enemies with high health. On higher difficulties, these cowardly gunmen will be the bane of your existence and constantly lead to you being knocked down. The second boss of the second game takes this to an extreme with a room with moving floors and security cameras that fire rapidly at you if you end up in their sight, and when you add in the missiles the boss is firing, oh god.
Anarchy Reigns usually throws relatively tame enemies at you (barring the Giant Mooks). But the majority of players will be filled with dread at the sight of a Cybrid Joe. For starters, they are invincible to any grab attempts from the player and will usually just run away from them, making catching them a pain. But it gets worse when you get to fighting them. The Cybrid Joes have a huge array of attacks and none of them can be stopped with one of your own. The majority of them deal some terrifying damage on higher difficulties and they usually start these attacks when you're in the middle of a combo and completely helpless to avoid the attacks. And this isn't getting into the Cybrid Bar Bot...
Arcuz II has the Skeleton Mages. These guys don't have that much health, but they can shoot painful fireballs, cast an even more painful area spell, create a black hole that sucks you in and hurts a lot when it explodes, curse you which greatly lowers one of your stats for a very long time (multiple stats can be affected), and worst of all, they can revive dead foes to full health!