Most Epic Raid Boss fight ever...?

[Grimbold of Skullcrusher]

Algalon The Observer for me.

[Deleted]

For me I would say Lich King normal 10man.
I'd made an apply for a guild, the first one I even did actually, and I got accepted. Already head over heels happy about this I got to raid as soon as I joined, and did so a few weeks. We killed 11/12 normal in those weeks and I was so happy that I've gotten this far with the guild, and it was time for the Lich King that we had been wiping on for some days. It was time for the last try of the evening, and I guess we all became a bit more focused just for that reason. We pulled and managed to reach phase 2. This was great we thought, since we usually didn't even get past phase 1. We handled the defile well, and we killed the val'kyrs fast and easy. We reached the second transition and someone yelled "Pop bl now, we need it for the adds!". And so we did, and somehow we managed to reach phase 3! This was the first time we had made it so far, and we became extremely focused; This could mean a kill. We handled the spirits well, and we even popped our pots for a change. When we hit 13% or so our tank died, and we frenetically had a hunter kiting Lk for the last 3% while we other managed to nuke him down. It was such an epic feeling when we finally saw him casting Fury of Frostmourne. The next day at school, I met my IRL friends who didn't make it into the guild and they were so jealous of me getting to kill the Lich King. It was probably the greatest moment in my wow-history.

[Deleted]

Algalon and Lich King. Kael'thas would be up there too, if only for the pure bliss of finally getting him down and getting our attunements for T6 content.

[sulfuric]

40 man 4 horsemen.

[Rédempteur]

I've always loved Thorim's hard mode in Ulduar.

[Toxigen]

I never reached KT in Naxx 40 (we had finally poached enough tanks for 4H when it all ended), but I'd reckon that would have taken the cake.

Most epic kill was definitely pre-nerf M'uru for me, though. We put absolutely everything we had into getting that fucking boss down before Blizz trivialized it. Was pretty funny having 20-ish guildies that weren't LWers prior to Sunwell buying up all the mats from the AH with our alts with skinners out farming for a week straight too.

Go go drum rotations.

[Ethes]

Heroic Ragnaros:
Has all the aspects of a great fight. Very challenging and interesting until the end. Only drawback was having NPC's helping you! I don't like NPC's helping me kill stuff okay?!
Heroic Al'Akir:
Perfect balance between person skill (don't get knocked off, in tornado, etc) and raid awareness (don't let feedback fall off, etc). 3D movement seem'd a big pain in the ass for some poeple. Still don't quite understand why!
Chess:
Whiping is impossible! How awesome was that!
Shade of Aran:
As I was playing a hunter back in the day, this was great. No problems with silence or movement at all. Except those noobs that kept moving while flame wreath was cast..

There were definitly more awesome fights out there, but these are just some of my experiences. Heroic Ragnaros at #1 though

[Vektorix]

Covering my raid experience between early Burning Crusade and early Cataclysm:

1. Lady Vashj (Serpentshrine Cavern). I was co-GM of a guild on Akama that had taken people from guilds that had failed, or who had not been able to get a spot in one of the top guilds on the server, and built a team that had broken free of the "Kara-guild" shackles. When we went 5/6 and 3/4, people on the server started paying attention to us, but when we killed Lady Vashj, after a month of effort, we really announced our arrival. Was never so proud of our team as when we finally killed that bitch of a boss.

2. Zul'jin (Zul'aman) Before our 25 person guild got really up to speed, we spent a lot of time in Zul'aman, which was quite a challenge for players just in Karazhan and Badge gear. Hexlord Malacrass was really a pain, but Zul'jin took a lot of effort and coordination and awareness, and it was a long and well designed fight. Our 10m group struggled with Malacrass for a couple of weeks, and then Zul'jin for several lockouts, especially holding it together during the last two phases. We never focused on bear runs, but just getting that place cleared was an accomplishment.

3.. Kel'thuzard in Naxxramas 25m. Not for the fight itself, which wasn't particularly epic or hard, but the weeks when we were working on Immortal, everyone was wound so tightly that it could have been tank and spank and it would have seemed ridiculously over-the-top. When we finally got The Immortal (and our Black Protodrakes) it was such an incredible relief, I am tempted to say orgasmic. Sadly we only accomplished The Immortal once - every other try someone blew it on the last boss. But it got done, and there were 25 really happy people there that night...

[Eazy]

Lich King and Algalon are the most epic raid bosses fight in this game for me.

[Deleted]

For me it was Lich King 10-man. We weren't the best guild in the world but the feeling I got when we killed him has been hard to beat :3

[Keashaa]

1) Archimonde - my dear Archimonde, the first boss I ever encounter where the death of one dps could lead to a wipe of the entire raid thanks to soul charge. The boss was just a pain in the ass with fear (need a PvP trinket for a PvE boss ), grip of the legion, air burst, doomfire... that bosses teached me the lesson that you can play as good as you want... if there's one idiot in your raid, you cannot succeed...

2) Lich King heroic - so much trys, so much hatred... sooooo good when we killed him. Oh defile, I hate you...

3) Attumen the Huntsmen - my very first raid boss... it felt so great to kill a boss in a raid

[Deleted]

Ragnaros(Fireland) and LK 25man heroic!! Epic fights!

[Outofmana]

1. 40man 4horseman by far, never seen such a sick fight again.
2. 40man Gothik, probably saying this because it was a priest fight.
3. Twin Emps.

(4. 40man Sapphiron, the only true resist fight, epic fight with zero mana regen having only to heal your group with rank 1/2 PoHs, amazing to do as a healer)

[Reptar]

I have a couple for various reasons.

1) Lady Vashj. I started raiding in BC, so if you were new to raiding and also do remember this fight, it was extremely epic.
2) Yogg Saron. but no watcher's style. When I got Death's Demise, it was one of the most tense/exciting feelings I've had from raiding.
3) Heroic Rag. I always raided in a guild that was above average, but never top tier or hardcore, and we played very well in Cata. We netted a kill on heroic rag that put us around top 50 US at the time, so that had to be one of the most satisfying kills for me ever as it rounded out the tier very nicely.

[Deleted]

If I had ever done it at level Ragnaros would be a good contender. His emergence was just an epic oh s*** moment. Too bad we were there at L70 meaning he was dead in about 30 seconds which killed that moment in the same 30 seconds xD.

My most epic fight would be Mimiron. First you fight a tank, then a turret and a flying head... only to be combined to one boss who's gonna kick your ass again. The way through the spark of imagination made for one hell of an entrance as well. Hell I loved every one of the keeper fights. They had style. Too bad I never got the chance at Vezax and Yogg at level though since the summer holidays hit and well... half of the raid group was gone after that.
Runner-up would be the Lich King. Remorseless winter is prime example of the power he radiates and makes him bad-ass.

[Deleted]

Heroic Ragnaros.

[Resentful]

Nothing will compete with Algalon well maybe Heroic LK and Yogg-saron haha but Algalon is pretty much the best looking fight in the entire game despite the mechanics were kinda dull (He did hit extremely hard at least )

[Kurzior]

Lich King is definitely up there in terms of just feeling like a really epic fight. The environment (both visual and audio) was extremely well done.

Ragnaros, same thing. Just felt like a really cool encounter.

Most memorable? Heroic Beth'tilac. Went in after a few hours of work and finally downing heroic Baleroc. Decided to just mess with the fight for the last 20 minutes or so of raid. End up 1-shotting her, partially because our dk taunted and kited here with rocket boots as she enraged to give us the last few seconds we needed to kill her.

Side note, Will of the Emperor is a pretty cool fight too. Love the narration on that one.

[Goatfish]

My top 5 in no particular order as a shaman healer:

25 Heroic Professor Putricide
25 Algalon
M'uru
Kalecgos
25 Sartharion +3 (before you could just burn it)

[Hexotic]

40 man thaddius in naxx.... I still have nightmares...