Vire

The Vire (バイア, Baia), is a bat-like demon that appears in The Legend of Zelda, Link's Awakening, Oracle of Ages and Oracle of Seasons, as an entity made up of Keese. The Vire tends to live in areas of darkness, like its Keese relatives, and even tends to split into Keese when injured, although Link can dispel this enemy by using a strong weapon, like the Magical Sword or the Fire Rod.

The Legend of Zelda
First encountered in The Legend of Zelda, Vires are large, blue devils. encountered only in labyrinths. When harmed, they split into two red-colored Keese, which float around the room like regular Keese. After dispatching the red Keese, if Link exits and immediately returns to a room, the Vires will all be back, since they haven't truly been killed. If it is hurt by the arrow, Magical Sword, or any weapon which does at least four damage, it will instead die.

Link's Awakening
In Link's Awakening these rare and fast flying creatures appear in only the hottest of dungeons, swooping down at random to try and harm Link. They fly around shooting Fireballs, which can be blocked with a Sword swipe, and after three or four of them, will swoop down at Link. Three blows will take it out, and cause it to explode into two Big Keese. The easiest way to defeat these monsters is to use Link's Hookshot. A zap from the Magic Rod kills it without causing it to split.

Oracle of Ages and Oracle of Seasons
Appearing in both Game Boy Color titles: Oracle of Seasons and Oracle of Ages, this red bat plays the role of henchman to both Veran (Oracle of Ages) and Onox (Oracle of Seasons). Depending on which game is played first, Vire will begin as an underling of the villain Link is currently up against. Vire also appears at various points during Linked Games to cause various trouble. In both games he is the miniboss in the sixth dungeon (Ancient Ruins/Mermaid's Cave). He will fly around evading Link and firing energy balls at him. After hitting him several times he will split into two smaller bats and they will try to tackle Link, one swipe of Link's sword takes both of those bats down.

Four Swords Adventures
In Four Swords Adventures, Vires appear in The Swamp and the Desert of Doubt. Once they reach a specific area, a Vire will fly around the Links, preventing them to progress. This incarnation of the Vire cannot be killed.

Trivia

 * Its name, "Vire", may be a contraction of the word "Vampire."
 * Gomess is another entity made up of Keese-like cratures, the Bad Bats, that appears in Majora's Mask.