DethI

"Nightmares shall never vanish, so long as I live.""

- Dethl

Dethl is an immensely powerful Nightmare-Demon, who passes from slumber to slumber to seize control of them, and serves as the main villain and final boss of The Legend of Zelda: Link's Awakening. The villain is often referred to as the Shadow Nightmares, or simply the Nightmare, in which cases Dethl is the name given to its final form. Given that the final form is considered the real one, it has little impact.

Characteristics
Dethl is a shapeless black form with shinning yellow eyes, born from fears and bad dreams, who can warp and distort itself, and assume any aspect it wants. When it transforms into someone, it gains their powers and skills. Its main form is just a gigantic eye that has two swinging arm-like structures.

DethI sometimes refers to itself as "we", implying that it is made of many nightmares, forming a hive-mind of sorts. However, this can also mean that it referred to itself and to the nightmares it spawned. Whether it can manifest in the real world, and invade more than one sleeping mind, leaving the others under the control of its spawns, remains unknown.

Being a literal living nightmare, Dethl can invade any dreams manipulate them as it likes. Its dominion lasts as long as the dreams it invades, so it preserves them by preventing his victims from awakening. It has immense powers, and influence over minds, as it has access to its victim’s and enemies’ thoughts, memories and fears, drawing power from it. It can draw sleeping minds in the dream it controls, or spawn other Nightmares under its command and uses them to swarm its victim's dreams. The more control it gains on a defined oneiric world, the more powerful it becomes.

DethI is power-hungry, ambitious and cruel, for it wants a domain to rule and does not care for its slumbering victims. It seems to revel in its victim’s fears, using such fears against its enemies during battles. It is somehow implied that it seeks to increase such fears. However, in a strange twist it seeks to save the world that would be lost if its victim were to awake. However, it clearly does it for its own selfish gain.

The Legend of Zelda: Link's Awakening
When the divine Wind Fish created a world through its dreams, DethI invaded it and locked the Wind Fish in an everlasting nightmare, swarming the island of Koholint, which was created from that dream, with monsters and evil forces and plaguing the life of its inhabitants.

As Link was returning to Hyrule by sea after the events of the Oracle of Times/Oracles of Seasons games, his ship was caught in a storm and sunk. Link then derived unconscious, floating on a wooden debris, and soon enough got caught by DethI as well, who transported him onto the oneiric Koholint Island; probably because the Wind Fish was sleeping nearby.

DethI knew that Link had defeated Ganon twice, during the course of Oracles and A Link to the Past. (This is noted when DethI transforms into Ganon during the final battle, using Link's own memories.) As such, it put as many traps and obstacles as it could in Link's path. Yet, this proved no match for the legendary hero, who destroyed the Shadow Nightmare's spawns and collected the eight musical instruments needed to free the Wind Fish and himself from DethI's evil grasp, which DethI's spawns were keeping away.

Link eventually faced and defeated the Shadow Nightmares. One can wonder whether the DethI is truly dead after that it vanishes, or if it returned among the dreams, though it stated that it could never be truly destroyed.

Links awoke along with the Wind Fish. The Island of Koholint faded away, leaving Link floating on a piece of shipwreck debris. The game ends as Link looks up to the heavens and sees the Wind Fish fly away into the clouds.

Boss Battle
The battle against DethI is long and challenging. Link better be well prepared and have as much health as possible. Stage 1: Zol Form: The first phase is by far the easiest. DethI first resembles a Zol blob monster, which jumps at Link for a few times before disappearing into the ground and resurfacing somewhere else. Link must sprinkle the Magic Powder on it after its jump, three times. Any other attack merely makes it disappear into the ground. Stage 2: Agahnim Form: DethI's second form resembles Agahnim and fights similarly by warping in the room and firing energy balls, that Link must strike with his sword (or his shovel) to send them back, four times. When it fires an energy cross that divides into four smaller spheres when hitting the wall, Link must dodge both the cross and the spheres. Stage 3: Moldorm Form: DethI transforms into Moldorm, the first boss of the game. Dethl is more resilient than the actual boss but there is no chasm he can push Link into, making the battle easier. The Shadow Nightmares run across the room and must be struck on the tail (where its real face is located) six times, or with three to four Spin Attacks. The more wounds it gets, the faster it becomes and it starts bouncing erratically on walls. Stage 4: Ganon Form: DethI transforms into a doppelganger of Ganon, wielding a double, double-edged halberd. It conjures many flaming bats one after the other, hurls his halberd like a boomerang and glides away to repeat the process. Link must either charge at it with the Boots and the Sword combines, or strike him with Spin Attacks, six times. Stage 5: Lanmola Form: The Shadow Nightmares' fifth form looks like a giant Lanmola worm monster. It is very fast and catching up with it can be tricky, but it is very easy to defeat, taken down with but one strike of the Fire Rod. Phase 6: Final Form: DethI's final form (assumed to be its real one) attacks by constantly swiping its two tentacles. Link must use the Feather to jump over the tentacles, and jump back in front of the boss, to shoot arrows in its open eye. Link can shoot up to three arrows in the open eye, and must shoot DethI fifteen times. When wounded enough, the demon becomes faster and starts swinging its tentacles diagonally. Link can also finish DethI off with one strike of the Boomerang, but this is much harder for the eye must be wide open.

Quotes
"We were born of nightmares... To take over this world, we made the Wind Fish sleep endlessly! If the Wind Fish doesn't wake up, this island will never disappear! We would have been the masters of this place... But you had to come here and disrupt our plans! Heh heh! You can never defeat us!!! Let's rumble!"

- DethI taunting Link before the final battle.

"This island is going to disappear... Our world is going to disappear... Our world... Our... world..."

- DethI's last words.

Hyrule: Total War
In this popular fan-made game, DethI is one of the Druthulidi, a group of extremely powerful Eldritch Abominations who kept threatening Hyrule throughout history. DethI is here referred to as a female, and proves horribly sadistic and disgustingly cowardly, who can invade and control many dreams at once, driving her victims to madness if she haunts them for too long, to the point that they kill themselves and become undeads under her control. She is driven by a never-ending hunger and spends a large part of the story controlling the demon Bongo Bongo, born from one of her victims.