Hi and welcome to my threat of... The most annoying enemies on the video games
I don't know if there's already a threat of this?.... but I'll try to put different
Many people add something like Minecraft Creepers and Mario bros Hammer bros... so I'll more interesting enemies okay?
I'll put in top order.. Not in difficulty... is going for more frustrating to less frustrating
-Rules for reply-
-1 You can reply adding your annoying enemies no more than 5
-2 videogames boss are not allowed
so let's go!!

5- Silent hill 4, Wheel chairs
The wheelchairs are a very annoying enemy in Silent hill during the hospital in groups and is impossible to kill
they take you a lot of life and cause damage even if you didn't touch them.... I know what are you thinking why you didn't put the Twin victims?
easy because you can kill the Twin victims but no the Wheelchairs!

4-SMB 3, Big Bertha the fish
aaaahhhhh!!! I hate this stupid fish!
just say it... you also hate the level where this fish eat you in world 3
you can kill him... but reapers after a bit of time... and you die only by touching it  >

3- Earth Jim 2, Grannies
well I think those enemies are so annoying... and why I put them?
the first time I played the game those grannies make me fail all bonus cuz was the first time playing... at the begging they look easy
but if one of them touch you just... and just at the level final.... is so irritant!!

2-Fnaf 2, Balloon Boy 
for those who played Fnaf 2
what happen if balloon boy enter in your office and stay there laughing?
exactly you lose... Balloon boy is pretty annoying and appear in the worse moments like Mangle
but for my self I hate more Balloon boy

1-Zombies ate my neighbors, Boogeyman
AAAAHHHHH!!! I hate this enemy much he's pretty annoying... he only appears when you open a box or doors
and why is so annoying? Easy there's no! And I mean No way to avoid it attacks, is only to bad luck and take a heal bar from you
sometimes when you're at low Hp it appears when you're searching some Hp and AAAhhh!!!!

Dark sword Z : my most annoying enemy is: Huff 'N Puff from paper mario. he is incredibly powerful, and he just is not a fair enemy. he always uses all of these cheap moves, and they make him hell to try and kill. i mean, of course it's possible to kill him, but dang nintendo, this game is for KIDS! kids would break their controllers in frustration killing this guy, i bet. 

http://www.mariowiki.com/Huff_N._Puff

#5 Slimes. THERES JUST TOO MANY OF THEM! Every game with them
#4 Goblins. They hit to hard if they are a higher level. Dragons Dogma
#3 Bandits. They think they own everything, which they do not, therefore they are annoying. Two Worlds
#2 Dark Elfs. There are too many of them and they hit too hard. Too Human
#1 Neochu. I GET POISENED EVERY SINGLE TIME! Final Fantasy I

Zubat! Can't escape! Fine, I'll fight them... the Pokemon hurt itself in confusion! Allow me to drain life while I'm at it with Leech Life. I always hated Zubat.

Those round alien jelly blobs in Metro 2033. You had to defend this guy from one end to the other with infinitely respawning jelly blobs that went straight toward that guy you're trying to defend. 

Wallcrawlers from Ocarina of Time in the Forest and Shadow Temples. They brought you back to the beginning of the temple. Could you imagine wall crawlers in the water temple? That would have made an already infamous temple even more infamous. 

the Grim Reaper from Madworld. I died so many times because he is there to one hit KO you. I've restarted many times from those levels because even at full health a single attack from him kills you instantly. 

Enemy types in general that heal themselves. Final Fantasy is no stranger to that. Also, Pokemon that use "recover" like Starmie and Alakazam, or when trains decide to use a Full Restore or Hyper Potion upon finally getting a Pokemon down a sliver of health. 

The Flood from Halo, an overrated game. Level 8 of Halo was WAY too long for its own game and it was hordes and hordes of respawning Flood and the developers decide to copy and paste within copy and paste WITHIN copy and pasted level. Ugh! Those flood...

Enemies that randomly become invincible: These show up from time to time in games, and always manage to prove the hard and fast rule that making an enemy invincible for any reason, for any length of time, is almost always a recipe for frustration. Above we have the “shielding” affix in Diablo 3 which just makes elite groups of enemies invulnerable for random intervals. It does not make them stop attacking however, and therefore you are usually dead because of it. Resident Evil and Dead space have those regenerative 

The enemies that run up to you with a knife and instantly kill you. You're firing at them and until they die are bullet sponges. They just grab their knife and machete and at full speed come straight at you. Far Cry 3 and Spec Ops the Line are notable examples. 

The boss battles that spawn little enemies that you have to face while taking on the boss as well.  

Infinitely respawning enemies: Medusa heads from Castlevania and many enemy types from the Ninja Gaiden games from the Nintendo Entertainment System, especially the birds. 

Lastly, I'll throw those types of enemies that come up in tiny swarms that run up to you just to blow up in your face. They don't necessarily do a lot of damage, but they are an annoyance. Also the ones that stick to your face blinding your vision. Bugs from the Resident Evil series, Head crabs from Half Life,  

Wow this post was a lot longer than I had anticipated. I feel like better being able to complain on the Internet even though it doesn't make a bit of difference in the world...

Dark sword Z :  
1. Skree from Metroid. You can only kill by aiming up, and they propel down to you so fast you really can't do much.

2. Mr. Lakitu from Super Mario Bros. Idk if he counts, as its the spinies he throws that get me bad. 

3. War Wasps from Metroid Prime. The never leave you alone, and the endlessly spawn until you destroy the nest. They have projectiles as well as melee. Wasps? yea right. -.-

4. Torch Hollows from Dark Souls. You'd think that of all the hammer wielding bosses in the game, the unclothed, zombified torch wielding hollows wouldn't be worth a dime of your attention. Wait until you get hit. If you're lucky enough to escape their stun lock, The run at you like mad men and the damage from those torches will two to three shot you? Yet when you wield a torch, only 5 damage. Wow.

Frost Trolls from Skyrim. Beefy as hell, and if you werent using destruction magic, (specifically fire), Then you are forced to melee. You can't take a hit from them without sacrificing a chunk of health. They appear in numbers as well, gaurding important objects. I would've said wisps instead, but at least wisp mother doesnt respawn and isnt impossible to kill. Same with Ice wraiths.

Well, I can't possibly remember all the annoying enemies I've been playing, but here's what I can remember, plus some in video games I've been playing recently, so they're fresh in my mind.

Super Smash Bros (N64) - Fox
Legend of Zelda, Ocarina of Time - Peahat
Mass Effect 3 - Banshee
Legend of Zelda, Ocarina of Time - LikeLike
Skyrim - Dragon

1. All the enemies except the final boss in ICO. Their entire existence revolves around them annoying the heck out of you. They come at you (or rather at the princess you're trying to escape with) at scripted parts of the game, often at pretty inconvenient times for you, and they will just knock you down because comat is terrible in this game, and then they take the princess and Game Over. Happened to me so much in that game.

2. The Metal Slimes from Dragon Quest V. They're not hard at all, their attacking strength is terrible. In fact, they're very likely to run away from you. However, this is not what you want. You want to defeat these guys for massive EXP., but their defense is ridiculous so they're almost unkillable. And to top it off, they're ultra-rare. Blah.

3. Let's include the mandatory Pokémon in here. But no, I'm not mentioning Zubat, even though I just did. I'm gonna say Spinda, in Pokémon Ruby/Sapphire. At least Zubat evolves into an awesome Crobat later on, while Spinda on the other hand is nearly useless.

4. The Green Bugs from Rayman. These guys are really good at ducking below your punches, and following up by hovering in the air and kicking you backwards. If you just happen to stand behind a gap which leads to your death... well...

5. Metallo's flying minions from Superman Returns. You have to fly up to them if you want to defeat them. Well, the controls aren't very polished in Superman Returns, so this can already be a drag. But they fire kryptonite laserbeams which drain Superman's energy crazy fast. Best way to deal with these pests is to just crash into them three times with your superspeed. It's easier than you'd imagine, but it feels really awkward and sluggish...

My top 2 wouldn't really count as video game enemies but they're my enemies and they are found in video games. They're also added in for comical effect.

5. Green Zombie from RE: Outbreak. The spores in this mo-fo are so annoying. Being poisoned is probably one of the most annoying things that could happen to you. Especially since sometimes blue herbs are hard to come by on that level.

4. Pendulum from Silent hill 3. I hate wasting my bullets on these good for nothing pieces of crap. They're hard to fight with a melee weapon too. Not to mention, they emit an annoying screeching noise when they're close to you.

3. Ghasts from mine craft. I once died because I focused too much on the ghast floating above me, I didn't notice the lava pit I ran into. They're just really annoying with their distracting balls of fire.

2. Mine craft Lag kills. It's an invisible enemy. One day you're happily frolicking about in the server, on your OP mount wearing your OP armor wielding your OP weapon. Then suddenly you lag and somehow end up in a wall and suffocate to death and lose all your well earned sh*t. I just purely rage out at that point. I didn't do anything to deserve it.

1. Josh (Human Player) that f*cking ginger from the LOTR mine craft server I used to play in. He was playing on the good side and I was playing on the evil side. We're good online friends but in that server, we were downright vengeful enemies. He's so passionate about eliminating evil that he keeps threatening to kill my character. I'm pretty much chill with it though. When our characters finally bumped into each other, I called a truce because I wanted to show him something cool I built. I told him to follow me and he did. After I eased up in the conversation, I casually mentioned I wasn't wielding a weapon. Then he straight up murdered me. A frikken defenseless player in the middle of a truce. That f*cking douche bag.

5: Any version of the Big Eye (Mega Man games). These behemoths do tons of damage and soak up attack like BB's.
4:Clickers (The Last of Us). They take eons to kill but can kill you instantly.....
3keletons (Minecraft). Ever since an update, Skeletons now shoot absurdly fast and are my biggest killer in early game.
2ark Nuts (Twilight Princess). These guys infest the final area and are responsible for about a million of Links deaths under my control.
1:Those things that pop out of the paint(Super Mario Sunshine). Ever time these guys attack you you get all slippery and makes it difficult to fight any foe. VERY aggravating.

#1 The Marlboro/Oscar family, Final Fantasy series. Unless you have the right equipment/junction to save you from status, they are basically invincible and can confuse the hell out of you
#2 Prism Flowers/Zeon Guards, Shining Force II. They only appear in 2 fights, but man do they make those fights hard. They shoot at you whenever you are in a straight line from them, making strategy VERY difficult.
#3 Scary-cat enemies, various franchises. Metal slimes (Dragon Warrior), Core enemies and Mimics (Lufia), just to name a few, are worth a ton of experience but their defenses are too high and they escape easily. Not cool
#4 Chimera, Shining Force I. Their regular attack is all right, but most of the time they spew fire and can easily kill the most overleveled character. I always hated the fights starting with the one before Ramaladu.
#5 Tradoshians (?), Dark Forces: Jedi Knight. Not only to they have the strongest gun around, but they can actually smash you with it if you're at close range.