Essentially a large Wizard, this boss guards the Maze Island Palace, and can be defeated only by using the Reflect Spell to turn his own magic attacks against him. Carock throws his attacks and warps at a very high rate, so Link must defeat him quickly before it's too late.
Carock is the first boss in the series whose defeat requires turning his own magic against him, later expanded upon with Agahnim before becoming common in later games.
Carock bears a resemblance to the Magician who tricked the Prince and placed Princess Zelda under a sleeping spell. Despite the similarity, they cannot be one and the same, as Carock is one of the guardians of the temples that protect the Triforce of Courage, created by the King of Hyrule himself.
Carock is referred to as a Wizzrobe in the NES Game Atlas, despite the smaller wizard enemies in the palace never being referred to as Wizzrobes.
Carock in The Adventure of Link
Carock warping around the room
Carock's sprite from the Japanese version of the game
↑"To defeat the sly and quick Wizzrobe, Carock, Link must use Reflect. After activating the spell, crouch at the left of the screen and wait for the magic to give the Wiz some of his own medicine." (NES Game Atlas (Nintendo), pg. 68)