The Legend of Zelda: Link's Awakening/Characters/Nightmares

The Wind Fish's nightmares, are the primary antagonists of The Legend of Zelda: Link's Awakening, part of the Legend of Zelda series. They are a group of shadows haunting the Wind Fish's dreams. Link, protagonist of the game, was to defeat the nightmares to escape from Koholint Island. Each Nightmare (save for Dethl) held an instrument needed to wake the Wind Fish.

The term "Wind Fish's nightmares" often refers to the collective dungeon bosses that inhabit the game, the end boss is often called the Final Nightmare or Dethl.

Dethl
Whether or not the Final Nightmare is one being or a group of beings is unclear and subject to dispute, but they are all uniform black, save for one or more green-tinted eye(s). The only original being that appears is Dethl, and that is the name that the nightmares (collectively or as a single entity) are often addressed as. Regardless, the Final Nightmare is the end boss of the game and is implied to be responsible for plunging the Wind Fish into an eternal nightmare.

The Final Nightmare represents the most evil and terrifying entities that haunt the dreams of the Windfish. Also, a tap into Link's mind is demonstrated by the Nightmare taking the form of several of Link's previous enemies and a final form which bears the name Dethl. It bears a slight resemblance to Vaati (a reoccurring villain of the series).

Powers and abilities
The nightmares reflect previous enemies: Agahnim, Ganon, Moldorm, Lanmola, as well as a giant blob and Dethl, a creature with long arms and one giant eye. They possess the same powers as the actual beings they reflect: Ganon's Shadow uses a trident and fire, Agahnim's Shadow uses magic, Moldorm's Shadow charges after Link, and Lanmola's Shadow burrows and emerges from the ground. The giant blob just attacks Link, and Dethl spins its long arms around and attacks Link.

Dethl's weak spot is its large eye, which can be effected by arrow shots, or, if the player acquired it, one direct hit from the boomerang item.