Obi-Wan Kenobi

At the beginning of The Phantom Menace he is apprentice to Jedi Master Qui-Gon Jinn whom he accompanies to Naboo, the planet ruled by Padme Amidala. On the death of his master at the hands of Darth Maul, Kenobi honoured his master's final wish to train Anakin Skywalker, a young boy who showed tremendous potential with The Force.

Unfortunately, his training of the boy is not adequate to prevent him from being seduced by the Dark Side of the Force and siding with Supreme Chancellor Palpatine in his plot to become Emperor and purging the Jedi Order. Eventually, Kenobi and Skywalker fight and the teacher manages to wound his student so badly that Skywalker needs extensive medical prothestics that became central to his new identity as Darth Vader.

However, this clash does not halt the rise of the Galactic Empire and Kenobi was forced into hiding on the planet Tatooine. Some thirty-two years after the events on Naboo, he rescues Anakin's son, Luke Skywalker from Tusken Raiders[?] when he was out in the wilderness of Tatoonine looking for a droid determined to deliver a message to the old Jedi Knight. Kenobi eventually hears the message of Princess Leia Organa asking for his assistance in delivering the schematics of the Death Star to Alderaan. While Kenobi is ready to help, he decides his best contribution is to reestablish the Jedi order. To that end, he takes young Luke Skywalker under his wing and teaches him the ways of the Force with the intention of fully training him on Alderaan

When the Millennium Falcon is captured by the Death Star, Kenobi manages to deactivate the tractor beam to allow the ship to escape, but his return to the ship was cut off by Darth Vader who challenges him to combat. While occupying Vader and his forces, he creates the necessary distraction to allow Luke and his friends to get to the ship. Sacrificing his hope for escape, he allows Vader to strike him down, only to have disappeared at the instant of the final blow.

As turns out, Kenobi was not gone entirely. Rather, he became a spirit who advises Luke as a mentor the Sith cannot touch.