Obi-Wan Kenobi
A legendary Jedi Knight, Obi-Wan Kenobi began his Jedi-career as Padawan learner to Jedi Master Qui-Gon Jinn. On Tatooine, him and Qui-Gon discovered Anakin Skywalker, the boy who was to bring balance to the Force. After defeating Darth Maul, a Dark Lord of the Sith, Obi-Wan became a Jedi Knight and began training Anakin in the Jedi ways. Anakin became Obi-Wan's Padawan learner and they fought together in the Clone Wars.
When Anakin gave in to the temptations of the dark side and became Darth vader, Obi-Wan thoguhtfully and successfully hid Anakin's offspring from Vader himself and Emperor Palpatine. He took Luke to live with his Uncle Owen and Aunt Beru Lars on Tatooine, and Leia was taken to Viceroy Bail Organa of Alderaan. Obi-Wan went into hiding on Tatooine for many decades and accepted the name Old Ben.
Obi-Wan shortly trained Luke in the ways of the Force, but sacrificed himslef to Vader on the Death Star and became one with the Force. Kenobi's spirit continued to guide Luke, first at the Battle of Yavin in the destruction of the 1st Death Star, then in instructing Luke to finish his training with Master Yoda, and later to tell the truth about Luke and his father Darth Vader..