Most boss fights in the 3D Zelda games are pretty epic, if only in appearance at times (Fyrus, I'm looking at you). But the one that always stuck with me was the fight with Dark Link in Zelda 2.
It comes out of nowhere and catches you totally off guard the first time through the game. You wouldn't expect a second boss fight right after the almost assuredly grueling battle with Thunderbird; that boss seems more than hard enough to be a last boss, especially since you go through the entire dungeon before you reach him AND have to use a special spell to even be able to fight him. And if you don't know the trick to make the Dark Link fight simple (who ever did, the first time through?), it is a really epic fight.
Sky Render - Sanity is for the weak.
