Obi-Wan Kenobi was a Jedi Master who served the Republic prior to the Clone Wars and before the rise of the Empire.
Kenobi discovered the young Anakin Skywalker on the planet Tatooine and brought him back to the Jedi Temple on Coruscant. Following the loss of his own Master, Obi-Wan began teaching Skywalker the ways of the Force.
However, Kenobi could not prevent Skywalker from falling to the dark side. Skywalker turned on the Jedi and was proclaimed Lord Vader. Obi-Wan was able to survive Order 66 and retreated to Tatooine.
From there, he watched over Anakin's son, Luke Skywalker. Obi-Wan eventually trained Luke and joined him on a mission to confront Vader on the Death Star. There, in a final duel against his former student, Kenobi did not survive.
In an alternative storyline, Starkiller can face off against Obi-Wan on Tatooine.
Obi-Wan Kenobi was a brave and daring Jedi Master, never failing to do what was right. He was a diplomat just as he was a warrior, forming several friendships within the Jedi Order. However, for all of his skill, he was not able to understand his Padawan Anakin Skywalker - a failure that eventually led to the fall of the Jedi Order.