Obi-Wan Kenobi is the enigmatic Jedi Master created by George Lucas for the original and prequel Star Wars trilogies. In his initial appearance in the first produced trilogy, episodes IV-VI, he is played by Sir Alec Guinness. The trilogy centers on Luke Skywalker’s quest to destroy the Galactic Empire, and to become a Jedi Knight. Kenobi lives on Tatooine, as does Luke. He is one of the remnants of the once great Jedi society, which was all but destroyed by Darth Vader and the Emperor.
In Lucas’ prequel trilogy Episodes I-III, Obi-Wan Kenobi, played by Ewan McGregor, is still an apprentice to Jedi Master Qui-Gon Jinn. He and Qui-Gon encounter the boy Anakin Skywalker on Tatooine, and Qui-Gon agrees to train Anakin. Obi-Wan greatly opposes this training, making the argument that Anakin is too old (nine years old) to begin training and has too many strong emotions to make a good Jedi. In this assessment, Obi-Wan is absolutely correct — it is Anakin’s passions that bring about his downfall. Nevertheless, when Qui-Gon is killed by Darth Maul, Obi-Wan agrees to assume the training of Anakin and recognizes his huge potential to manipulate the force.
By the second film in the prequel trilogy, Star Wars: The Attack of the Clones, Obi-Wan Kenobi has been elevated to the rank of Jedi Knight and is the main teacher for Anakin. He’s still young, about 25, and he’s frankly not a great teacher. Anakin’s skills are unquestionably excellent, but Obi-Wan fails to see just how much Anakin is led by his emotions, and especially fails to realize that Anakin has begun a prohibited relationship with Padme Amidala. In the third film Obi-Wan fully realizes how far Anakin has strayed from Jedi precepts, and the master must make the very difficult choice of crippling, but not killing, his pupil in a final duel. After the duel, the birth of Luke and Leia and the death of their mother Padme, Obi-Wan is charged with the task of watching over Luke and protecting him from perception by the transformed Anakin/Darth Vader.
The original trilogy, which is set approximately 20 years after the prequel, creates a few logistical problems. Sir Alec Guinness plays Obi-Wan Kenobi, and he’s clearly much older than the 28-30 year old Obi-Wan at the end of Episode III. It would be difficult, however, to dispute Guinness’ mastery in this role, which originally defined the character and made such an impression on film audiences. Charged with watching Luke, Obi-Wan has spent years in relative hiding, mastering the ability to come back from the dead, and fully committing himself to Jedi principals. Perhaps his insufficient training of Anakin, who he initially presents to Luke, as having been “killed by Darth Vader,” has aged him prematurely. The Obi-Wan Kenobi of the original trilogy is certainly a much wiser man and has lived as a hermit while Luke grew up; thus he’s had plenty of time for contemplation.
He has definitely learned that it is possible to come back from death, something hinted at at the end of the prequel trilogy. Toward the end of the original Star Wars Obi-Wan allows Darth Vader to kill him, making it possible for Luke and his friends to escape the Death Star. His ability to come back from the dead in spirit form, and continue to direct Luke in his training means Obi-Wan Kenobi continues to make appearances in all three of the original trilogy films.
Furthermore, even though he has died, he and Jedi Master Yoda are able to fully train Luke to be a Jedi, and to help Luke act in the manner required to destroy the Empire, and convince Darth Vader to become Anakin again in final moments of the third original film. Through training Luke, Obi-Wan sees his main goal in life — the training of Anakin and his final redemption, come to fruition. He also takes part in the prophecy that Anakin will restore balance to the force, something not achieved until Darth Vader is able to put aside his Sith training and save his own son.