Jalhalla

The immense leader of all Poes and ghosts resides in the core of the Earth Temple. Jalhalla is not a tough foe, nor does he attack often. The trick to bringing him down is to reflect light with your Mirror Shield directly onto him, causing him to fall and lay still. You must then lift the giant off the floor and toss him into one of the columns of spikes on the walls. This will cause his body to split into dozens of Poes for you to dispose. To make the task easier you can use the Hurricane Spin technique (if you've learned it) to quicken the job. Repeat this process and destroy all the Poes to free the Sage.

His reincarnation is found in Ganon's Tower later in the game. He is defeated for a second time (in the same fashion) to break the seal to door leading to Ganondorf

He also makes an appearence as the boss of The Swamp in Four Swords Adventures.