Wart is the first of two minibosses in the Great Bay Temple in the video game Legend of Zelda: Majora's Mask. He has the appearance of a gigantic eyeball. He had several smaller eyeballs around him. Once defeated, Wart exploded. Another Wart can be found inside a shrine around the area of Ikana, and defeated the same way.
To defeat Wart, Link must first destroy enough of the smaller eyeballs. He can use the Hookshot to pull them toward him and then attack them with his sword. The battle is easier if most of the eyeballs are destroyed before Link attacks Wart directly. Arrows are the best weapon to use against him. After taking enough damage (or if all the eyeballs are destroyed) Wart will go to the ground and start attacking Link himself. Link can use arrows or his sword to attack Wart. After a few hits, Wart will be defeated, and will be destroyed in a massive bomb explosion.
A miniboss in Legend of Zelda: Twilight Princess, called the Deku Toad, acts in a similar manner to Wart. In addition, it being a giant toad is also similar to Wart, the main villain from Super Mario Bros. 2.