Kholdstare

The boss of the Ice Palace begins as a pink puffy eye encased in a block of ice. Link must use the Fire Rod to break him out, at which point he splits into three identical parts which can be hit with the Fire Rod or with the Sword. Upon his defeat Link receives another heart container and the crystal containing the fifth imprisoned Maiden.

During the fight ice will fall down from the ceiling and break up in multiple pieces to try and hit you. As that is the only real danger Kholdstare is not that hard to defeat.

Ironically, Kholdstare (in its original frozen form) bears a striking resemblence to Frostare from The Legend of Zelda: Four Swords Adventures.