Great Deku Tree

The Great Deku Tree is a recurring character in the Legend of Zelda series. Although the two Great Deku Trees that appear are different, their purpose remains the same; they protect the spirits of the forest.

The Legend of Zelda: Ocarina of Time
In the beginning of the Imprisoning War, the Great Deku Tree was cursed by the evil Gerudo Prince of Thieves, Ganondorf, as a punishment for not giving him the Kokiri's Emerald. Knowing Link's destiny and that his time is short, the Great Deku Tree sends Navi the fairy to retrieve the boy and asks him to break the curse on him. Although Link braves the dungeon inside the Great Deku Tree and defeats Queen Gohma, it is already too late to save the tree. Before he dies, he tells Link about the creation of Hyrule by the three goddesses Din, Nayru and Farore, and how they left behind them golden sacred triangles when they departed for the heavens after their labors were completed. The Great Deku Tree gives Link the Kokiri's Emerald and tells him to seek out the Princess of Destiny who lives in Hyrule Castle. The Great Deku tree then withers and dies.

After Link completes the Forest Temple and awakens Saria the Sage, he is transported to the grove of the withered Great Deku Tree. He is surprised by the little Great Deku Sprout that pops out of the ground. It is this sprout that tells Link the truth about his past, and reveals that Link is not a member of the Kokiri, but a Hylian who was given to them by his mother, who died soon after. It is possible that this is the same tree Link comes across in The Wind Waker, and that the Koroks, the leaf-faced tree creatures, are evolved Kokiri that the Great Deku Tree once fathered.

The Legend of Zelda: The Wind Waker
A Great Deku Tree, which may or may not be the aforementioned Great Deku Sprout from Ocarina of Time, appears again in The Wind Waker. This Great Deku Tree lives in the Forest Haven together with the Koroks. After Link rescues him from ChuChus, he is given the task to rescue a Korok named Makar who has crash-landed in the Forbidden Woods and to aid him, the Great Deku Tree gives him the Deku Leaf. After Link rescues Makar, the Great Deku Tree gives him Farore's Pearl.

When Link first encounters this Great Deku Tree, he is speaking the Hylian language. His dialogue is translated into english during the Second Quest.

Freshly-Picked Tingle's Rosy Rupeeland
The Great Deku Tree appears again in Tingle's Rosy Rupeeland. This one is likely not the same Deku Tree as either of the two previous ones. The Deku Tree's appearance is similar to that of the one from Ocarina of Time; he is once again the protector of the forest, which is called the Deku Forest. This may or may not be a version of Kokiri Forest and the Lost Woods, and shares certain characteristics with those areas.

The Deku Tree's heir, who is growing below the Deku Tree, has fallen sick due to all the damage that Humans have done to the forest. The Deku Tree implores Tingle to get Pure Dew to save his Heir. To this end, he allows Tingle to enter the dungeon below him, known as the Deku Temple.

Once Tingle completes that quest, the Deku Tree rewards him thoroughly and then withers up and dies, leaving his Heir to become the next Deku Tree.

This is the only version of the Great Deku Tree known to demand payment in Rupees.

Speculation
Since the game details the beginning of Tingle's story, it quite possibly takes place before Ocarina of Time. However, since Tingle is known to have originated in Termina (see The Legend of Zelda: Majora's Mask), it is possible this game takes place in Termina, which would make this Deku Tree the Terminian equivalent to Hyrule's Deku Tree.

If that is not the case, and the game takes place in Hyrule, then it is possible that the Deku Tree in this game may be the father of the one in Ocarina of Time; making the Deku Tree's Heir seen in this game would later become the Great Deku Tree in Ocarina of Time.

Possible other appearances
It is speculated that the Great Deku Tree's stump appears in Twilight Princess. It is located to the south of the Great Bridge of Hylia in the Lanayru Province. The stump is fairly large, indicating that it may have been a Great Deku Tree. However, it is unknown if this stump is the Great Deku Tree's or if it is the Deku Sprout's. Also, note that there are ChuChus in the Forest Haven in The Wind Waker, as well as underneath the stump in Twilight Princess. However, the stump in the Lanayru Province is more likely the dead tree that was above the Water Temple in Ocarina of Time. An even more widely believed inference is that the Forest Temple of Twilight Princess is in fact the remains of the Great Deku Tree of Ocarina of Time. This can be determined from the temple's location being inside a giant tree the size of the Deku Tree, and the presence of the Kokiri symbol on the doors of the temple just as it was on the doors inside the Deku Tree in Ocarina of Time.

Another speculation holds that the Deku Tree's stump is located in Ordon Village. If one compares the map of Ordon to the map of Kokiri Forest, they appear to be the same area, with certain differences (which could be attributed to the passage of time between Ocarina of Time and Twilight Princess). Following this map, the clearing where Link meets the Great Deku Tree in Ocarina of Time is the water-hole in the village. In the center of that hole is a protruding structure, from the bottom of the water, which could be the dried-up and crusted remains of the original Great Deku Tree.

Another possibility is that the Deku Tree in Twilight Princess is actually the Forest Temple

There is also a theory about the Great Deku Tree appearing in the original The Legend of Zelda. It is believed that Level 1 is a dead Deku Tree.