Dark Link

Dark Link, also known as Shadow Link, was a recurring villain throughout The Legend of Zelda. He is often thought as a doppelgänger of Link. He debuted in Zelda II: The Adventure of Link as the final boss of the game. Dark Link appears in many games, but it is uncertain if this is one, single entity or if each game has its own, individual Dark Link, but it is suggested that the same being appears in several games.

Characteristics
Dark Link is everything that Link is not and everything that he is at the same time. It would be accurate to say he is Link's exact opposite, for whatever Link desires, Dark Link wants the opposite. He holds the skills of the Hero but instead of all things good, he is bad, this making it possible that Dark Link was created from all of the negative thoughts and feelings in Link, the Hero of Time. It is also possible that Ganon brought life to Link shadow using dark and evil magic. He is filled with evil and a need to destroy the Hero and the line of the Hero. Dark Link in Zelda II: The Adventure of Link is the same person as the one in The Legend of Zelda: Ocarina of Time possibly, but the Link is different. Unlike Dark Link, Link is not immortal and eventually dies. However, several of the incarnations of the Hero of Time had to face Dark Link, or some of the mass-produced Shadow Links. It is unclear if Dark Link works for Ganon directly, or merely fights the hero on his own accord as he did in "Zelda II".

It seems that multiple Dark Links can be created at the same time, which all seem to be seperate entities than the iconic villain. These are often identified as "Shadow Links" in-game, rather than Dark Links, oddly. These are most often much weaker and less skilled than the iconic Dark Link villain.

Creation
Dark Link's creation is not often elaborated upon in the games he appears in. However, it is generally assumed that Ocarina of Time has his backstory. As Link is traversing through the Water Temple, he comes upon a surreal room matted with water, a skyline, and a small tree in the middle. Link's shadow suddenly leaves the floor without him noticing and hides behind the tree, causing Link to lose his reflection in the water as well. After Link has no success opening the door on the other side of the room, he turns around and is ambushed.

The weaker, mass-produced Shadow Links all come from various sources. In Four Swords Adventures, they are continuously spewed out by a magical "Dark Mirror", obviously being separate entities than the original Dark Link. In Oracle of Ages, Veran produces four of her own, though they are the weakest to ever be displayed. In the Gameboy Advance version of A Link to the Past, four Shadow Links appear in a hidden dungeon, and it is stated that they represent the final challenge to the Hero before he can claim the Four Sword.

In the Four Swords manga, Dark Link is said to be Link's doppelganger from the Dark World; he does evil acts to be noticed, since people turn their backs to their shadows. This Link is also afraid of the light. In the end, he realizes that he is a part of Link, which made him a hero. He destroys the Dark Mirror, killing both Vaati and himself for the sake of the world. Before Dark Link dies, one of the four Links tells him, "You are one of us."

Zelda II: The Adventure of Link
Dark Link's first appearance is in Zelda II as the final boss of the game. Link is forced to fight him after the defeat of the Thunderbird, in order to win the Triforce of Courage.

Dark Link appears when Link approaches the Triforce of Courage. The lights go out, and Link's shadow jumps away from his body and then proceeds to attack with his sword. He is defeated by Link, who after the ordeal revives the original Princess Zelda. .  Nor is he at the time referred to as Dark Link, instead known simply as Link's Shadow. It is possible that he is a separate entity from the OoT incarnation of Dark Link. On the other hand since he was summoned by Zhahz it's also possible that he's just like Dark Link resurrected.

The Legend of Zelda: Ocarina of Time
Dark Link appears as a Mini-Boss of the Water Temple, appearing as Link's shadow in a strange, illusionary room. before attacking him. His voice is the same as Links, only in a much deeper tone. He can use some of the Link's sword attacks and is one of the hardest enemies in all the game. He can counter Link's sword attacks easily, and can actually counterattack the stab: a rather arrogant move where he jumps onto Link's sword, pinning it in place, and slashes at Link. However, Link can make short work of him using Din's Fire, which he can't block, and if he manages to land a hit with the Megaton Hammer, Dark Link will cease defending himself and simply allow himself to be beaten (the Biggoron Sword and Broken Giant's Knife are also quite effective in the fight). In this game, he has a shimmering appearance and sports a pair of glaring red eyes. Upon defeat, Dark Link screams and falls through the floor, leaving behind a Red Rupee. The mysterious room loses its illusion, and the door forward opens.

This game would mark his first chronological appearance, but his origins in this game have not been clarified. It could be presumed that this Dark Link survived through the ages to do battle again in Zelda II, but this is never directly suggested and, considering the storyline of that game, seems improbable.

The Legend of Zelda: Oracle of Ages
In Oracle of Ages, the game's main villain and final boss Veran summons multiple copies of Dark Link throughout the battle. These copies are significantly weaker than the real Link, and are mainly used by Veran as a distraction. They cannot attack save for bumping into Link, and drop a heart upon defeat.

The Legend of Zelda: A Link to the Past (Gameboy Advance Version)
After clearing several sub-challenges included in The Legend of Zelda: Four Swords and the main game itself, a hidden palace appears. In this palace's final room, Link must battle four Shadow Links, each with a different tunic and different powers. Their tunics correspond to the colors of the Links that hold the Four Sword: Green, Red, Blue, and Purple. Each Shadow Link has a different power, and the powers of the previous ones. These powers include using Link's charge, sword beam, a jump attack, and the hurricane blade.

The Legend of Zelda: Four Swords Adventures
In Four Swords Adventures, Ganon uses Shadow Link to deceive Link into drawing the Four Sword from its pedestal, releasing the wind mage Vaati, who abducts The Seven Maidens. Shadow Link is a main antagonist in the game, a recurring mini-boss, and has a new trademark giggle. Many Shadow Links appear in the game, all mass-produced by the Dark Mirror. However, one of them seems to survive and play as the main copy, but whether this is the iconic Dark Link or not is speculatory.

Many Shadow Links appear to harass the heroes using various tools, such as giant bombs and Link's own weaponry. They can assume the coloration of one of the four Links, requiring that particular one to defeat it. Shadow Link is killed at the end of the game by the effects of the Mirror.

The Legend of Zelda: Twilight Princess
Dark Link has only a cameo appearance in Twilight Princess. Three Dark Links symbolize the interlopers that attempted to break into the Sacred Realm in the vision of the creation of Hyrule given to Link by Lanayru. Dark Link is not fought, however, and is merely a visual tool.

The player can also see what may be another possible cameo by sending Link into the basement of his home; Link should wield the lit lantern and use it to navigate his way across the room to a mirror, then extinguish the lantern. Link's reflection in the dark strongly resembles Dark Link.

Super Smash Bros. series
Dark Link makes a cameo appearance in Super Smash Bros. Melee as the opponent in the event match Link's Adventure, though it is just Link at Level 9 in a black "skin".

Dark Link is playable as a palette swap for Link in Super Smash Bros. Brawl and also appears as a boss in event mode, where he has 200HP. However, in the image in which he is seen as a boss in event mode, he doesn't use the palette swap, but instead appears completely black, similar to the Dark Link in Super Smash Bros. Melee. Strangely, his damage meter shows the picture of his palette swap. Also, Toon Link, another playable character, has the dark skin as well.

Comics and Manga
In the manga version of The Legend of Zelda: Ocarina of Time, Dark Link makes one appearance. While Link is training with Impa in Kakariko Village, Dark Link appears from the well and attacks Link, only to be defeated.

In the manga of The Legend of Zelda: Four Swords Adventures, Shadow Link appears and is expanded upon. When he first appeared, he easily defeated the four Links as the four sword had lost its power. Later, he attempts to tempt the purple Link to evil and otherwise to sabotage the Link's mission. This failed, as the Purple Link was lying to him all along, and then joins with the other Links and bests Dark Link. He is later recreated by the Dark Mirror. Although he is commanded to fight against the Links, he chooses to help them by pointing out Gufuu's weak point. However, he soon realizes that as long as the Dark Mirror exists, Gufuu will be invincible, and destroys the mirror, despite warnings from Gufuu that he would die if the mirror was destroyed, which turned out to be true. Before dying, he reconciles with the other Links. His nature is explained as "The shadow version of Link from the Dark World". He is later said when dying, "Shadows stay behind their masters, but I turned it around and defeated y'all's enemy." After this, he then turned into light.