Morpha

Morpha is the Boss of the Water Temple from Ocarina of Time. It is a very simple boss. All Link has to do is avoid its water tentacles, avoid the spikes on the wall, and when the core ball floats into one of the tentacles shoot it with Link's Longshot, then hit it with the Master Sword. After a few hits, the water will eventually evaporate into the ceiling and leave a drop which transforms into a Heart Container.