Princess Zelda is part of Hyrule's royal family. She is usually kidnapped or imprisoned by Ganon/Ganondorf and saved by Link in the Legend of Zelda series.
Princess Zelda is one of the Main Protagonist in the Legend of Zelda series. She is the princess of all of Hyrule and, is recognized as one of the links to the gods. Zelda is historically given the Triforce of Wisdom, which she usually uses to aid Link in his quest to stop Ganon. She has been portrayed as a kind, wise , and thoughtful person; in Twilight Princess she abdicated her right to the throne, to preserve her people.
Zelda was usually shown to have a slight crush on Link, this was changed in the Twilight Princess series; where Link is attracted to another.
In The Legend of Zelda Ocarina of Time, To further help Link without being discovered by Ganon; Zelda transforms herself into Shiek of the Sheikah.
In The Legend of Zelda Windwaker, Zelda lives through a decedent of hers known as Tetra, Tetra is a rough and tough pirate that aids Link across the great sea, she later awakens as Princess Zelda.