Sometimes, in an otherwise mediocre game, there is one boss that is just several leagues better than anything else in the game. For me, that boss is Stallord in The Legend of Zelda: Twilight Princess.
A giant skeleton that you have to hit by basically skateboarding into him? Super rad. His 2nd phase is the most fun Zelda boss battle, hands down. Riding up a giant pillar on your "skateboard" and jumping into him, just smacking this fool in the face.
I have a separate save file right before this boss so I can replay it over and over.
What are your favorite bosses? The most fun, the most memorable, the most difficult? Lay it on me!