Bail Prestor Organa is the Viceroy and Prince of the planet Alderaan, the husband of Queen Breha Organa, and Princess Leia Organa's adoptive father. In the waning days of the Old Republic, he also serves as Alderaan's representative in the Galactic Senate, succeeded later by the adult Leia.
As a prominent member of the Senate's Loyalist Committee, Organa realizes early on that the Separatists are a serious threat, and are going down a path that could only lead to war. He reluctantly approves of granting vast emergency powers to Chancellor Palpatine.
By the time of Star Wars Episode III: Revenge of the Sith, Organa is convinced that Palpatine has no intention of relinquishing his emergency powers at the end of the war as promised. He holds secret meetings with other concerned Senators, such as Mon Mothma of Chandrila, Fang Zar of Sern Prime, and Padmé Amidala of Naboo who now believe the Chancellor has designs on seizing total control of the galaxy. When Palpatine reorganises the Republic into the totalitarian Galactic Empire, Organa cofounds a secret resistance organization that would evolve into the Rebel Alliance.
In the aforementioned film, he witnesses the slaughter of a young Jedi Padawan by clone troopers outside the Jedi Temple at the start of the Great Jedi Purge. After that, he immediately begins searching for surviving Jedi. He rescues Masters Yoda and Obi-Wan Kenobi. In the meantime, his ship (the Tantive IV) has received a message from the Jedi Temple, which orders all Jedi to return to the planet Coruscant, as the Clone Wars are over.
He becomes a close friend of Senator Padmé Amidala of Naboo, Leia's birth mother. After Padmé's death, he adopts Leia to protect her from her father, Anakin Skywalker, who has become the Sith Lord Darth Vader and had helped Palpatine exterminate the Jedi.
Organa is killed when Alderaan is destroyed by the Death Star.
The official site clarifies this issue somewhat, stating that Bail Antilles and Bail Organa were both slated to appear in The Phantom Menace, but Organa's footage was excised. In the screenplay, Bail Organa seconds the motion of no confidence in Chancellor Finis Valorum's leadership, and Bail Antilles is nominated to succeed as Chancellor. Both were intended as two separate characters. Nevertheless, because his scene was cut, Bail Organa was recast for Attack of the Clones.
The Expanded Universe uses the appearance of the actor who played Organa in the cut scene, Adrian Dunbar, to represent Bail Antilles.