What are your favourite missions/quests in games?

My favourite quest is whodunit from oblivion, and the Stalingrad mission from COD 1. They can be from any genre.

Get the shadow skull in Dark Messiah of Might and Magic.

I laughed so hard at the quest in skyrim (or oblivion I can't remember) where you pose as "the gourmet" for the DB

It was skyrim, I also found that amusing

I also like 'whodunnit?'. Most of the DB quests in oblivion were good. I also liked the quest in FO3 where you test Moira's rat repellent.

Going after Shaundi at the end of Saints Row 3 with http://www.youtube.com/watch?v=4UpqLhYQz28 being played in the background. I was actually going after the other guy but when that song started playing I just had to turn around. It was epic.

Suicide Mission in Mass Effect 2. Nothing else Bioware has done in the last 10 years compares IMO, and it was very surprising they didn't do something similar for Mass Effect 3. They had everything they needed right there.

The Milkman Conspiracy in Psychonauts is great.

The three hidden stages on SoulCalibur 1 mission mode.

Shame the rest wasn't so epic.

Recently finished this level on my playthrough. I'd put it on my least favourite list. I can't even count how many times I died/reloaded.

Anyways, the last level of Resistance 2 is one of my favourites. Quite satisfying.

This and the last american mission

Thief: The Dark Project - The Sword
It's still probably the most original and most fun level I've ever played.

Thief: Deadly Shadows - Overlook Manse
http://www.youtube.com/watch?v=_IfttUuCac0, by Eric Brosius really makes this level magical.

Phalanx, the thirteenth colossus in Shadow of the Colossus. It's a mission/quest of sorts, and it's amazing.

The second-to-last act in Metal Gear Solid 4, Twin Suns.

The Paris Catacombs/Streets portion of Deus Ex. Oh man, I will forever adore that level. So dark and foreboding, yet containing a hint of tranquility with that piano tune playing in the background.

Assault on the Control Room in Halo CE

Yeah that was amazing too.

The Fighter's Guild quest in Oblivion in which you take Hist Sap; Whodunit? was pretty fun, too. A Night To Remember in Skyrim.

Thief 2: sabotaging the Soulforge
Thief 2: trail of blood
Thief 3: Shalebridge Craddle
Deus Ex: Hong Kong

Good Egg Galaxy from Super Mario Galaxy
Of Glitz and Glory from Paper Mario: The Thousand Year Door
Chapter 6 from Super Paper Mario
Chateau de Chucklehuck from Mario & Luigi Superstar Saga
The Wasteland Survival Guide from Fallout 3
You Gotta Shoot 'Em in the Head from Fallout 3
Tranquility Lane from Fallout 3
They Went That-a-Way from Fallout: New Vegas
That Lucky Old Son from Fallout: New Vegas
A Brain's Best Friend from Fallout: New Vegas
The Gourmet from TESV: Skyrim
"The Summit" from Journey
The Factory of a Better Tomorrow from LittleBigPlanet 2
Act IV from Metal Gear Solid 4: Guns of the Patriots

And that is all I can think of offhand.

For me the VersaLife building was the best part of that.

Least favourite level? I tried to make a joke, because getting the shadow skull is pretty much the MQ.