6. Twinmold
Twinmold is one of the stranger bosses, not because of how it looks or anything, it looks like your regular sand monster, but it's all because of the battle. You can become giant Link with your giant's mask and defeat him that way, or you can try attacking him without it and use different arrows.
That there are different ways to defeat this boss is fairly unique. Most bosses have close to one way to defeat them (you can defeat other bosses in different ways, but not with different techniques).
The area is almost dreamlike, you don't know where the desert ends. The ruins fit with the overall ruin feel of the dungeon, so nothing is very off with this boss.
The boss's overall design doesn't seem so great and original, but most of these sand monsters didn't fly. This boss is like a mixture of Argorok and Molgera, conquering the ground and the sky.
It's a boss with a common concept made much more creative.