Seven Maidens

The Seven Maidens were a group of seven young women who inhered magical abilities from there ancestors, The Seven Sages. Most of the maidens were named after the color they represented and wore, with the exception of the seventh maiden Princess Zelda. Although they possessed many magic powers they were captured by both the wizard Agahnim, and the wind mage Vaati. Although they share the same names there were likely two different groups of maidens throughout Hyrules history.

The Legend of Zelda: A Link to the Past
During Agahnim’s rise to power in Hyrule he began to capture and sacrifice each of the maidens one by one. By sacrificing the maidens he could reopen the seven sages seal on the Dark World and free Ganon from the realm. Agahnim was able to sacrifice all of the maidens except for Princess Zelda who was rescued by Link after she sent out a telepathic message to him to come to the castle and save her. Later on however, she was captured by Hylian Knights and sacrificed by Agahnim. After Agahnim had been defeated in the Light World, Link discovered that the seven maidens were still alive within the various dungeons in the dark world. Link then began to free each of them from there respective dungeons and revealed their history, along with Ganon and Agahnim's plot. Eventually when all of them had been rescued they helped Link break through the barrier surrounding Ganon's Castle where Link destroyed Agahnim and soon after Ganon himself. The seven maidens then returned to the Light World and celebrated the return of the real King of Hyrule.

The Legend of Zelda: Four Swords Adventures
In The Legend of Zelda: Four Swords Adventures the seven maidens were becoming worried about a dark energy they felt coming from the Four Sword Sanctuary (where Vaati was imprisoned at the time) and asked Link to come and protect them while they went and checked on the seal cast on Vaati. When they opened the portal to the sanctuary they encountered Shadow Link who then imprisoned them within seven crystals and placed them throughout various dungeons in Hyrule. Link eventually set of to rescue them. After Link had found them he used the power to repel evil within the Four Sword (which he was wielding at the time) to free them from there crystals. After each maiden was freed they used one of there magic spells (likely the Fairy Spell) to transform themselves into fairys to guide Link to the next maiden. Along the way they helped Link find the origin of Shadow Link and discover that man named Ganondorf who had stolen the trident from the pyramid and used Shadow Link to free Vaati. Eventually Link was able to save all of the maidens who helped him defeat Ganon and seal him within the Four Sword. After piece had been restored to Hyrule they ventured back of to each of there homelands within Hyrule.