Ook

Ook is a minor character from The Legend of Zelda: Twilight Princess. He is a white baboon who makes an appearance in the Forest Temple as the mini-boss of the dungeon. He is equipped with the Gale Boomerang, and uses it to cut down the main bridge leading across to the other side.

Apparently, Ook was possessed by some kind of Twilight Bug that resembles a Shadow Insect. This was causing him to go cazy and stop acting like himself. Once the bug is defeated, he returns to normal, and he actually helps Link defeat the boss by swinging across the battlefield with a Bombling, which Link can use to stun the boss with.