Favorite fights in WoW history

I've been reminiscing lately thinking back to my favorite fights in WoW. For me personally, I like fights with mechanics that create an intensity and excitement toward the end of the fight. The fight where it isn’t over until it's truly over. They don't necessarily have to be significant lore wise (it does help a little though). They also require everyone to be on their game and executing at a high level.

Here it goes.

#1 - H Anub Arak (ToC)
The raid itself was terrible but that boss stands out as my all time favorite. P3 was fun and for healers the leech mechanic lead to a very intense final 30%. Plus it had that achievement for no one dying for the entire raid.

#2 - Illidan Stormrage
This one comes in second mostly because the fight felt so significant. It's hard to put my finger on why it did but for me no fight since had the same feeling.

#3 - Nightbane
This didn't contain any ground breaking mechanics but I always felt it was one of the best tuned fights for its time. Healer mana acted as a soft enrage and lead to a very intense final 20%.

I'm not trying to say these are the "best" fights in the history of the game but these will always have a special place in my heart. I'm sure the people I was playing with at the time and how much I enjoyed their company impact this list as well.

What is/are your favorite fight/fights in WoW?