The Great Deku Tree is considered the "Father of the Forest"; he first appears in Ocarina of Time, where he is charged with watching over the Kokiri, a childlike race of forest spirits that live in the Kokiri Forest. He is an ancient, exceptionally large tree, with a humanoid face and big mustache.

When Ocarina of Time begins, the Great Deku Tree is suffering from a curse cast upon him by Ganondorf in an effort to gain the Spiritual Stone of the Forest, which is in the Deku Tree's possession. Knowing Link's destiny, the Deku Tree sends Navi the fairy to retrieve the boy, who is living among the Kokiri as one of them.

He asks Link to destroy the cause of the curse, a spider called Queen Gohma, within him. Although Link defeats Queen Gohma, the Deku Tree was doomed before Link had begun; before he dies, the Deku Tree gives Link the Kokiri Emerald and tells him to seek Princess Zelda at Hyrule Castle.