[Huckle]

Nefarian. We spent weeks working on that encounter, clear all of BWL in a night and the rest of the week just on him with the alt MC runs on Saturday. I played a rogue almost exclusively back then and the guild started off with only 2 spots in MC and then 3, when we started to make some progress in BWL we had somthing like 3-5 rogues depending on who was waiting at the orb. The best part about the weeks of attempts on Nef was the fact that some nights we had 10 or 11 rogues on kill squad duty taking down the larger Chromatic Drakonid.

[Beatzz]

Never did any old school raiding,

but for BC.. Probably Vashj/Kael

Wotlk.. Sarth 3d, even though it really isn't that hard

[Khayra]

Shade of Aran

[treyu]

Pre BC I would say it would have to be trash packs before c'thun, biggest c@#k block in the game imo at the time :P.

In burning crusade, its a toss up between pre pre pre hydross nerf, god so many bad memories. And then brute.

in wrath, everythings easy :P

[Durandro]

Only real problems I've had during my limited raiding experience is fighting the biggest boss of them all - server lag.

Seriously, wiped on Anub'rekhan three times in a row because of game-stopping lag. I was not well pleased.

[Turkson]

Lady Vashj was a major pain. I only know of a handful of guilds that would go back and make her part of their weekly clears. Everyone else killed her, got the vial, and quickly washed the nasty bile out of their mouths.

But honestly, most of Sunwell sucked too. Probably my least favorite raid. Don't get me wrong, Hyjal sucked too, but more in a monotonous way. Whereas Sunwell was just major major major heartache from the first trash mob to KJ.

[Gordonoth]

Prince, just for he fact that the amount of time dumb luck stopped us compleating that encounter is just stupid.

[Muryou]

vanilla wow: 4 horsemen
tbc: muru (pre nerf)
wrath: er probably one of the 5 man bosses. the real content is a joke

[Tentcale]

Never raided in Pre BC only did pvp >.<
BC - RoS in BT. People don't understand that no healing means no healing
WotLk - 25 Maly with twenty people =/

[Murdog]

Muru (Pre-Nerf of coarse) but also with that being the hardest boss to me it was also the most fun i ever had tanking (Sentinel Tank, and Entropius Tank)

[breaklance]

I found Kael to be the hardest for me personally. On many of our first attempts I was so busy still tanking things I couldn't safely pick up the sheild so praying for everyone else to be competant with their weapons usually ended in fail. But our dps eventually picked up enough that I had a few moments to grab the sheild and sword, then kael got...easier. If i can really say that about him.

[Aragante]

The one that I could never defeat, the SSC elevator monster( I always lost when facing him), the also hard to see but ever present know it all wanna-be raid leader( constantly had people out of postion), and obviously last but not least the omgithinkthe(insert important raid person's name here)isafkwhydidyoupull.

Runner's up: I didn't we were on Vent/TS even though you spammed it 700 times, What do you mean I am supposed to watch where I am going "American Idol" is on.

Honorable mention: You mean I should repair before I come to the raid so my weapon doesn;t break in mid fight and I am the OT.

In all serious, gamewise: Vashj, I just hated that fight. But C'thun certainly ranks up there and so does Ony

[Muffin Man]

I think this weekend when I was tasked with tanking Tenebron + adds in Sarth + 1. That was a mess, but oh so rewarding when I got aggro on everything.

Then that sinking feeling as -15000 armor meant I was using all my cooldowns and consumables desparately waiting for Tenebron to die.

[Kree]

Vanilla WoW - Battleguard Sartura & Nefarian
TBC - Muru
Wotlk - Sarth 3D

[Morgantis]

Vanilla -> C'thun
BC -> id have to say M'uru indeed (god i loved my first kill and i got my trinket though <3 )
WotLK -> Is there any content?

[Pyrea]

Kael'thas in TK pre nerfs.

Trash was an absolute pain
Then:
1st phase pretty easy
2nd dps check
3rd phase coordination healing and dps check
4th phase you get the idea
5th phase flying

Especially while being the warlock tanking capernian and needing to start running up to the MT 15 seconds before KT engages regardless of capernian living or not so the MT didnt get disorientated...that was interesting. As well as needing to use deviate surprise or else cap bugged and ran around no matter where I stood...

[Lexxaa]

Vanilla: cthun
TBC: muru pre-nerf, although Kael before his 100 nerfs and Vashj follow closely behind.
LK: so far sarth 3D 10man but not anywhere near previous mentioned.. still waiting for challenging content

[Lollo]

For me personnally as a tank it was Vaelastrasz (no KTM then), ROS could be exciting, Flames of Azzinoth, the 3 Drakes with Sarthy depending on how much you have to move around. Neither Keal'Tas Sunstrider nor Lady Vashj were particularily hard to tank although it took my guild some time to kill them. So they were probably the the hardest encounters.

[Subpar]

I also am one of those nonvanilla raiders...my answer though should give credit to vanilla raiders.

On my shammy I have cleared all LK content and on my hunter saw alot of BC content as he was my main. I think Malygos 10 is harder than 25 because of the chance to get quick 2 shot on phase 2.However the hardest figth for me to stomach is KT 25 man. I cannot imagin this fight back in the 40 man days. Even when we "do it right" and kill him and everything goes "smooth" it seems like a complete cluster. melee heavy groups having 3-4 people getting blocked people flipping cause a ranged dps keeps moving, a rogue not getting CC'ed fast enough after a MC and poisoning everyone near him, the MT getting blocked and kt going off on his own. In 40 man as heal lead and alot of the time raid assist lead i think i would have stressed out and quit playing haha.

[Postlife]

Vanilla - twin emps
BC - KT
wotlk - sarth 3D 10 man (took a few weeks there)