Sage

The Sages are a part of the The Legend of Zelda series introduced in A Link to the Past. They always operate as a group and seem to have the overall responsibilities of protecting Hyrule and as such, aid the Hero on his quest. Oftentimes, Link is required to save them or awaken them as (the new) Sages first. This usually is because the villain attacking Hyrule is aware of their powers, which are capable of stopping them. As such, they tend to take care of the Sages as soon as possible.

Many things about the Sages still are a mystery, and instead of answering questions, the younger games have made things even less clear. A Link to the Past introduced the Sages, back then known as the Wise Men and the Maidens. The Maidens were a group of seven girls, each descending of one of the ancient seven Wise Men. This system of a group of seven Sages was carried on in Ocarina of Time and Four Swords Adventures. However, in The Wind Waker, a second group was introduced. This group is responsible for keeping the Master Sword capable of defeating evil. It is unknown how this group relates to the first group and with how many they are. Twilight Princess complicated things further by seemingly featuring the first group of Sages. However, their nature was very different from that of the other incarnations of the Seven Sages. For one, they were ghost-like creatures, all looking the same, while all other Sages have been shown to be random people who just happened to be chosen as the next "Sage of (...)". Secondly, they seemed to be with only six, Princess Zelda not being part of their group, even though they were her tutors.

A Link to the Past
In A Link to the Past, the prologue mentions the Seven Wise Men (renamed "Sages" in the GBA re-release ) as the ones who, with the aid of the Knights of Hyrule, sealed Ganon away in the Sacred Realm long ago. During the beginning of the game, it is made clear that Agahnim, the King's righthand, is using his power to find and capture the Seven Maidens, who are the descendants of the Seven Wise Men and have inherited their status of Sage. Agahnim planned to send them to the Dark World one by one in order to destroy the seal that kept Ganon locked up.

Princess Zelda was going to be the seventh sacrifice, but she managed to telepathically send a message to Link, requesting him to rescue her. Link did succeed, but Princess Zelda was recaptured later, while Link was gone in order to obtain the Master Sword. Link then traveled to the Dark World to save each of the Maidens.

Ocarina of Time
In Ocarina of Time, the purpose of the Sages is further explored. Each Sage has their own temple somewhere in Hyrule and corresponds to a certain element. The elements presented in Ocarina of Time are: Forest (Saria), Fire (Darunia), Light (Rauru), Shadow (Impa), Spirit (Nabooru), Water (Princess Ruto) and possibly Time (Princess Zelda).

It was revealed that the original Sages built the Temple of Time to protect the Triforce against those who would use it for evil.

After seizing the Triforce and becoming the ruler of Hyrule, Ganondorf caused the temples of the Sages to become infested with all kinds of monsters, so that the Sages-to-be would not be able to fullfill their duty and aid Link. However, Link managed to get rid of them and help each Sage to gain their power. Eventually, Link fought Ganon in a one-on-one battle and managed to beat him with the Master Sword. When that happened, the Sages joined their powers and sealed the King of Evil into the Sacred Realm. As such, it is suggested that these are the Sages referred to in A Link to the Past

The Wind Waker
The Wind Waker introduced a new group of Sages. These Sages are responsible for keeping the Master Sword capable of defeating evil. It was not stated how big this second group was, but it at least consists of two Sages: the Sage of Wind and the Sage of Earth.

Before he was sealed away by the Great Flood, Ganon had ensured his victory by killing off these two Sages (Fado and Laruto). In order to stand a chance against him, Link had to find the new Sages (Makar and Medli), awaken them and safely guide them to their respective temples. After Link defeated Ganon, he and Tetra were picked up by Tetra's crew who apparently had also already picked up Makar and Medli.

Four Swords Adventures
On a stormy night, Princess Zelda and the shrine maidens fear that the reason for these events is that Vaati's seal is weakening. They summon Link and bring him to the castle so he can protect them while they open the portal to the Four Sword Sanctuary. When they do however, a shadowy figure appears from the portal. This figure was Dark Link, who then kidnapped the shrine maidens and sealed them in crystals. Link must then go around Hyrule and free the maidens from Vaati's wrath.

Twilight Princess
In Twilight Princess, the Sages (excluding Princess Zelda this time) appear as ethereal forms of old men. They are shown using the Sword of the Sages in a failed attempt to execute Ganondorf, which resulted in the destruction of the Sage of Water and the banishment of Ganon to the Twilight Realm.

Due to the appearance of the Sages' insignias on the robes of these ethereal Sages, it is possible these Sages are the spiritual incarnations of the powers of the six Sages awakened in Ocarina of Time, or in other words, the unawakened forms of the six Sages that were awakened in the future era. This would mean that while Saria, Darunia, Ruto, Impa, Nabooru and Rauru were the pre-destined physical counterparts, the source of their powers came from these ethereal Sages. This would explain why the six Sages appeared as normal beings in the past era of Ocarina of Time but gained great power later in the future era after the Hero of Time helped each of them to fuse with his or her own respective ethereal Sage (the ones shown in Twilight Princess). This would mean that these ethereal Sages, alongside the Oocca, were the original builders of the Temple of Time, as Rauru stated in Ocarina of Time, and, by extension, the creators of the Master Sword itself.