Link's Fairy Companion refers to several characters throughout the Legend of Zelda series. Link's Fairy Companions are female fairies that accompany Link on his adventures, offering advice and often playing a decisive part in the gameplay mechanics. Fairy Companions share certain personality traits, initially appearing as commanding and condescending towards Link, but grow to care a great deal about him over the course of the game. Despite their attitudes, Link seems to appreciate their assistance, company and friendship, even before they warm up to him.
Navi is a blue fairy assigned to Link by the Great Deku Tree at the beginning of The Legend of Zelda: Ocarina of Time. She becomes his companion, and follows through with this duty for the duration of Link's quest; even through his battles with Ganondorf. After Ganondorf is defeated and sealed away, she leaves Link's side in the Temple of Time's Master Sword chamber, without any explanation given.
Navi allows Link to Z-target certain targets; for instance, Navi can provide insight regarding the various enemies found throughout Hyrule, often revealing their weak points. When encountering an obstacle or object that can be manipulated inside a dungeon for the first time, she usually provides him with instructions on how to deal with it.
Tatl and her brother, Tael, are two fairies that befriended the mischievous Skull Kid. At the Skull Kid's bidding, they ambush Link at the beginning of The Legend of Zelda: Majora's Mask. Link gives chase, and is later impeded by Tatl, who is separated from her brother and the Skull Kid. She somewhat reluctantly agrees to work together with Link to escape the caverns in which they find themselves stuck. Initally, she only becomes his temporary ally until she is reunited with Tael and the Skull Kid, but the discovery of his true intentions convinces her to aid Link in stopping the Moon from crushing Termina.
Tatl functions much the same way as Navi; however, Tatl is decidedly more outspoken and opinionated than her, even going as far as to exasperatedly complain when Link asks for advice regarding an enemy he had already encountered in Ocarina of Time. As the quest progresses, however, she grows fond of Link, and is saddened when they part at the end of the game.
Ciela is Link's fairy in The Legend of Zelda: Phantom Hourglass. She encounters Link when he washes up on Mercay Island in the World of the Ocean King and remains with him throughout the game. Once Link completes the Temple of Courage, Oshus reveals that she is the Spirit of Courage. She allows Link to shoot Sword Beams once he has collected enough Courage Gems, and allows him to use the Hammer. At the end of the game she leaves Link to serve the Ocean King along with Leaf, the Spirit of Power, and Neri, the Spirit of Wisdom.
Whenever Link frees one of the Seven Maidens (with the exception of Zelda) in The Legend of Zelda: Four Swords Adventures, they transform into a Fairy and aid Link on his journey through the next level, which is usually the land the maiden watched over before her imprisonment. They will give Link various hints regarding story events and will occasionally converse with the next maiden found at the end of the level.
Leaf is one of three Fairy Companions appearing in Phantom Hourglass. His role in the story is not as significant as Link's main Fairy Companion Ciela. He is found in the Temple of Fire on the Isle of Ember; he opens a door in the Temple of the Ocean King, and later helps Link to find the Ghost Ship. Link can use Leaf to power up his Sword once he has collected enough Power Gems.
Neri is one of three Fairy Companions appearing in Phantom Hourglass. Her role in the story is not as significant as Link's main Fairy Companion Ciela. She is found in the Temple of Wind on the Isle of Gust; she opens a door in the Temple of the Ocean King, and later helps Link to find the Ghost Ship. Link can use Neri to power up his Shield and give him Enhanced Defense once he has collected enough Wisdom Gems.
Spryte was Link's Fairy Companion in the aftermath of Dark Link's defeat and the awakening of Princess Zelda. She only appeared in the Legend of Zelda animated series. She was very pushy and outspoken, and had a crush on Link. This caused her to become jealous every time Link tried to kiss Zelda, often using her magic to disrupt their romance.
Emheralda was Link's fairy during Agahnim's rise to power. She only appeared in the Link to the Past graphic novel.
Felicia is Link's Fairy Companion in the The Legend of Zelda: Link's Awakening manga. She was sent by the Owl to assist Link in his quest to awaken the Wind Fish. She starts rather aloof but eventually warms up to Link. She is kidnapped by several Moblins while Link battles a Hinox and used as bait to lure him to the Eagle's Tower.
The cursor in the Wii version of The Legend of Zelda: Twilight Princess takes the form of a fairy. It does not have a specific name, or play a role in the story, as it is used only for a cursor.
In Link's introductory cutscene, a fairy that looks remarkably similar to Navi is seen with him. Additionally, one of Link's taunts depicts a fairy with the same appearance flying around Link in the same pattern as a health-restoring fairy; however, this fairy serves no useful purpose.