Best Boss Battles

[Fishmonger]

The Goldeneye thread got me thinking about how good the battle against Trevelyan on the Cradle is. What are your favourite boss battles? Judge by any criteria you like(original, tricky, fun, difficult). Please don't mention anything about the new Zelda.

One of the best I think is the fight against The End in Metal Gear Solid 3. It's completely unique, there is so much freedom of movement and choice of tactics. It feels very tense too, and the amount of time it takes gives a real sense of the psychological battle between two snipers.