A Poe is a ghost enemy in The Legend of Zelda series of video games, one of concentrated hatred toward the world that freely roams graveyards and other haunted locales in Hyrule, as well as the overworld and dark places. They always carry their signature lanterns.
Ocarina of Time and Majora's Mask
In Ocarina of Time and Majora's Mask, they fly around until they spot Link, at which time they will charge at him, spinning their lanterns. Targeting Poes in these games will cause them to become temporarily invisible, although they will become visible every once in a while. Their lanterns remain visible when they vanish, allowing Link to at least dodge, block, and keep track of the invulnerable enemy until it reappears. Attacking a Poe while targeting it will cause them to run away, often going through walls in the process. When a Poe is defeated in these games, its physical body turns to ash, and the lantern it was holding drops and breaks, revealing its spirit. The Poe Spirit appears as either a purple flame with a sad face, or a green flame with a happy face, and disappears after a while. Before it disappears, Link can put the Spirit in a bottle, which is primarily used to sell for Rupees but can also be consumed, which can have strange (and usually negative, though not always) effects. As an adult, Link will encounter Big Poes, which can also be sold for monetary rewards or earn him a bottle from the collector. Poes are less common in Majora's Mask, but are worth more when sold.
Sharp and Flat
In Ocarina of Time, the ghosts of the royal composer brothers named Sharp and Flat tell Link about the Sun's Song and other music-related things after he defeats them in Kakariko Graveyard (Flat and Sharp fight like regular Poes). They explain their origins as composers of the Royal Family who were each researching a song, one that controls the sun, and one that controls the moon. They combined and composed their findings to create the "Sun's Song" as a way of controlling both. Once Link learns the song, he can use it to turn day into night and night into day. The brothers were going to reveal their findings to the king when they learned of Ganondorf's treachery. Unfortunately, the two took that secret and their song to their graves...literally. They are among the few characters in the game that still recognize Link after his seven-year hiatus in the Sacred Realm. In Majora's Mask, the Composer Brothers have a more direct role in the plot. Sharp had "sold his soul to the devil" and had imprisoned Flat in Ikana's Graveyard. When Link frees Flat, he tells Link about his brother's curse and reveals to him the Song of Storms, which has the power to lift curses and is used to defeat Sharp later on. Sharp had been haunting the spring that is the head of the river in Ikana Canyon. The Music Box House used the spring to keep the undead-repelling song playing, but the river has stopped flowing. Sharp attempts to kill Link with an unholy song (which is actually the Song of Healing played backwards), but when Link plays the Song of Storms, Sharp is purified and the river flows once more. Sharp then realizes the error of his ways and reveals that he knows how to get into the Stone Tower Temple, but he is only willing to convey this information to Link if Link will first fulfill his final request: Link must go see the king in the ruins to lay his soul to rest.
The Poe Sisters
There are four Poes known as the Poe Sisters: Joelle, Beth, Amy, and Meg. In Ocarina of Time, these Poes are the sub-bosses of the Forest Temple. As Link enters the temple proper, they steal the four torch flames necessary to activate the elevator which is used to enter the sub-basement where the boss's lair is located and use them to light their signature lanterns; as Link makes his way through the temple, he battles each of them one-on-one in order to relight the torches. They are also fought in a mini-game in Majora's Mask.
In the Explorer's Crypt of Oracle of Seasons, Link must defeat two unnamed Poe Sisters individually to progress, and then the other two as the mini-boss. One carries a lantern, leaving a trail of fire as it flies around, while the other carries a sword that it charges at Link with. Each of them first appears in a room that gradually darkens, eventually hurtling Link back to the dungeon entrance if he is too slow to flee the room. Link then encounters each of them in a room adjacent to the darkening room they had cursed, where he fights one of them. After these encounters, the sisters will fight Link together, forcing him to not only attack them, but also relight the lamps they extinguish, lest he be expelled back to the dungeon entrance as before.
The Poe Sisters in Ocarina of Time are named for the four main characters of Louisa May Alcott's Little Women.
Big Poes in Ocarina of Time are similar in appearance to regular Poes, although they wear orange robes instead of purple. There are ten Big Poes that adult Link can find in certain locations throughout Hyrule Field. While on foot, the Big Poes circle Link, keeping a safe distance from him, and shoot fire out of their lanterns. They do not turn invisible, but if Link fails to defeat them they eventually disappear completely, refusing to reappear until Link leaves and returns to the field. When defeated on foot, the Poe spirit is treated like that of an ordinary Poe. If Link encounters them on horseback, they behave differently. Rather than attack, they quickly fly away and disappear when they hit a wall. Link has to attack quickly using his horseback archery skills in order to defeat it. A Big Poe defeated on horseback is treated as a true Big Poe when bottled, and as a side quest, Link can catch and sell each Big Poe to the Ghost Shop at the gates of the fallen Hyrule Castle for Rupees. Once Link has turned in all ten Big Poes, he is rewarded with a Bottle.
The Big Poes that appear in Majora's Mask look nearly identical to regular Poes (including wearing purple clothing), but they are noticeably larger. A Big Poe appears as a sub-boss in the Beneath the Well dungeon and in the third night's open grave in Ikana Graveyard. It is summoned when three blue flames appear and merge. Defeating this Big Poe earns Link a bottle. This Big Poe attacks much like a normal Poe, but after each attack it teleports to charge Link from another direction, usually from behind. It will also hover higher than most regular Poes, almost requiring arrows to defeat it. The bottled Big Poe can be sold for 200 Rupees at the Curiosity Shop; however, one is also needed to trade with one of the Gibdos beneath the well.
The Wind Waker
In The Wind Waker, Poes harass Link by attempting to burn him with their lamps, and can jump into his body to possess him, reversing the player's movement controls. These Poes are invulnerable unless exposed to light, which causes their ethereal bodies to become temporarily solid (evidently causing them great distress, as the sudden change to their environment causes them to run around frantically). Poes are also shown to be ruled by Jalhalla in this game.
In Twilight Princess, a character named Jovani sold his own soul to the Poes. The Poes require the pieces of his soul to live, and can only be defeated by ripping out their souls. Because of this, there are a finite number of Poes in the game, and once one is defeated, it is gone for good (similar to the Golden Skulltulas of Ocarina of Time). Technically, you can beat the game having collected only five Poes, though it is very useful to collect every Poe Soul. After returning twenty Poes to Jovani, he rewards Link with a bottle full of fairy tears. After collecting all sixty Poes, his cat, Gengle, grants you unlimited silver Rupees (200 every time you speak with him).
In Twilight Princess, the majority of the Poes that Jovani sold his soul to were Poe Imps. Poe Imps are smaller versions of Poes, and can only be seen as floating blue lanterns while Link is human. To see their bodies, Link must transform into his wolf form and use his sense ability. When seen in this wolf form, Poes are bright bluish-white, with faces similar to those of the Skull Kid of the same game, and carry their lanterns with their feet, wielding large scythes for attack. Poes like the dark, so they are found only at night or in dark places like caves and dungeons. There are sixty Poe Souls scattered throughout Hyrule to collect, many of them difficult to find.
In an event similar to that in the Forest Temple in Ocarina of Time, four Poes (the only regular Poes in the game) steal the flames that open a door in the Arbiter's Grounds dungeon. These Poes are larger than Imp Poes, and wear cloaks. After being killed, the cloak remains on the floor (despite being ghosts, they have a scent that Wolf Link can track). One of the Poes that Link fights has the ability to make three clones of himself — an ability no other Poe has (except the Poe sister Meg from Ocarina of Time, another parallel to the Poe sisters). The clones circle Link, and one of them will eventually start to shine more brightly than the others, giving itself away.
Jalhalla is the king of Poes (and apparently Ghinis as well), and so is very large, similar to most of the series' rulers. Jalhalla resembles a gigantic version of the Poes from The Wind Waker, but has a differently shaped mask and a horribly bloated stomach. The name Jalhalla is likely based on Valhalla, the Norse heaven for heroes and home of Odin. Jalhalla himself was possibly based on Boolossus from Luigi's Mansion, as both are massive ghosts that result when several ghosts merged. The battle music when fighting Jalhalla is reminiscent of a French accordion.
Jalhalla appears in The Wind Waker as the boss of the Earth Temple and a sub-boss in Ganon's Tower, and twice in Four Swords Adventures as a boss. The first boss is Jalhalla's haunted mask and the second boss is a Big Poe containing the escaped spirit from the destroyed mask.