2. Mehrunes Dagon - The Elder Scrolls IV: Oblivion
The only thing worse than a pathetic final battle is a battle that finishes itself, without the player's aid. So, imagine my great dissatisfaction when, after putting over one hundred hours of time into my playthrough of The Elder Scrolls IV: Oblivion, I am forced to sit back and watch as Martin shatters the Amulet of Kings, transforms into the Avatar of Akatosh, defeats Mehrunes Dagon, turns to stone, and ultimately finishes the game for me. I leveled my primary and minor skills to the maximum extent for nothing! Throughout the entire game, you're constantly being educated and informed on the subject of Mehrunes Dagon, Daedric Prince of Destruction, Change, and Revolution. You're told of his transgressions and his future plans, which makes him quite a foreboding unseen presence during your adventures through Cyrodiil. When you're within the realm of Oblivion, you can't help but feel like he's somewhere, watching you, at that very moment.
This would have been my number 1 spot, but the battle to actually get Martin to the Temple of the One was actually challenging and enjoyable. This is because I was severely over leveled for that point in the game, making the enemies I faced quite powerful, so powerful that they were capable of killing Martin within a few attacks. The actual number 1 spot goes to something much,
much more anticlimactic.