Spirit

"Twilight covered Hyrule like a shroud, and without light, the people became as spirits. Within the twilight, they live on, unaware that they have passed into spirit forms... All the people know now is fear... Fear of a nameless evil..."

- Princess Zelda

During the events of Twilight Princess living inhabitants of Hyrule are transformed into spirits under the influence of the Twilight. Not all are transformed into spirits within the Twilight; it is believed that it's effects are partially negated by the protection of the Triforce. Ganondorf becomes the giant boar-like Dark Beast Ganon, Link becomes a wolf, whereas Princess Zelda remains in her true form. The Twili also remain in their true form due to them naturally inhabiting the Twilight Realm.