Yoda

Yoda has been training Jedi for over 800 years. Yoda was once the leader of the Jedi council before the Jedi was eliminated by the Emperor. As the Jedi were being destroyed, Yoda went into hiding on the planet of Degobah.

In The Empire Strikes Back, Luke Skywalker sees a vision of Obi-Wan Kenobi who tells him to go to Degobah to complete his training with Yoda. In The Return of the Jedi, Luke returns to Degobah to finish his training, only to find Yoda dying. Yoda warned Luke not to underestimate the power of the Dark Side. He told Luke that he must confront Darth Vader in order to complete his Jedi training. Then, Yoda died and disappeared, becoming one with the force.