The Nightmares showed up at Koholint want to rule over and to accomplish this, they must stop the Wind Fish from being awakened by playing the Instruments of the Sirens. They decided to steal them and have each of them hidden in one of the eight dungeons, which are their lairs. The Nightmares also created monsters and traps to stop Link from awaking the Wind Fish. They are intelligent enough in human speech as they talk to Link or try to scare or warn him from retrieving the Instruments.
List of Nightmares
Moldorm, known as Big Tail in Japan, is a segmented worm creature and the first Nightmare who guards the Full Moon Cello in Tail Cave.
Genie, known as Pot Devil in Japan, is a clown-like spirit in a jar and the second Nightmare who guards the Conch Horn in Bottle Grotto.
Slime Eye, known as Big Zol in Japan, is a huge, one-eyed blob and the third Nightmare who guards the Sea Lily's Bell in Key Cavern.
Angler Fish, known as Angler in Japan, is a huge angler fish and the fourth Nightmare who guards the Surf Harp in Angler's Tunnel.
Slime Eel, known as Hooker in Japan, is a giagantic eel and the fifth Nightmare who guards the Wind Marimba in Catfish's Maw.
Facade, known as Mat Face in Japan, is a disembodied face on the floor and the sixth Nightmare who guards the Coral Triangle in Face Shrine.
Evil Eagle, known as Albatos in Japan, is a huge, bizarre-looking eagle and the seventh Nightmare who guards the Organ of Evening Calm in Eagle's Tower.
Hot Head, known as Big Flame in Japan, is a disembodied head cloaked in fire and the eighth Nightmare who guards the Thunder Drum in Turtle Rock.
DethI, known as Shadow in Japan, is a shadowy being, the leader of the Nightmares and the final Nightmare encountered in the Wind Fish's Egg. It is the one who is responsible for putting the Wind Fish to sleep.