The Galactic Empire in Star Wars ruled through fear and intimidation. While this approach helped keep people in line and allowed the Empire to rule the galaxy for more than two decades, it does not inspire genuine loyalty. This is why numerous characters chose to bravely defect from the Empire. They knew what the Empire was doing was wrong and that they could no longer be part of their oppressive regime.
To be considered a defector, an individual needs to have made the choice to leave the Empire and to ultimately fight for the Rebellion instead. Bravery comes in many forms, but with these characters, it's determined by how much they risked when defecting, and through the courage that they showed when fighting back against the Empire.
Jai Kell
Jai Kell was a cadet in the Imperial Academy before intelligent Star Wars Rebels' characters, Ezra Bridger and Zare Leonis, convinced him to defect. They knew he was in danger after the Grand Inquisitor took interest in Jai's Force-sensitive abilities. Abandoning the Empire saved Jai's life, but it put him and his mother at risk in a new way.
Jai was pushed to make this decision by Ezra and Zare Leonis. He demonstrated more agency and more bravery as a member of Ryder Azadi's rebel cell four years after his defection, during which he helped liberate Lothal from the Empire.
Biggs Darklighter
Luke Skywalker's friend, Biggs Darklighter, is one of the first Imperial defectors to be introduced in Star Wars. After graduating from the Imperial Academy, he decided to defect to the Rebellion. He flew bravely during the iconic Battle of Yavin in the original trilogy where he risked his life in an effort to destroy the Death Star.
Biggs lasted longer than most of the pilots and was one of the last to tragically perish during the battle. As Star Wars canon continues to expand, there will hopefully be more stories that reveal more about Biggs' defection.
Thane Kyrell
The novel Lost Stars tells the story of Thane Kyrell and Cienna Ree. They joined the Empire together, but after seeing the destruction of Alderaan and how the Empire enslaved others, Thane defected from the Empire and joined the Rebellion. Being in the Empire with their best friend was their dream.
Leaving the Empire crushed that dream and challenged Thane's close relationship with Cienna, yet he knew it was the right thing to defect. He helped the Rebellion and the New Republic in their fight against the Empire, all while loving Cienna.
Wedge Antilles
Wedge Antilles is a rebel hero and one of the best pilots in the galaxy. He is the only pilot to survive the attack runs on both Death Stars. Yet, Wedge had originally been a pilot enrolled in the Imperial Academy. After seeing a rebel crew massacred after they surrendered, Wedge risked a great deal by contacting Fulcrum in the hopes of defecting from the Empire and joining the Rebellion. When Sabine Wren offered him a means of escape, Wedge seized the opportunity.
His bravery when flying against both Death Stars speaks for itself, along with his bravery during the Battle of Hoth and many other crucial battles. That courage continued in helping the New Republic defeat the Imperial remnants and then again, years later, when he joined the Resistance's fight against the First Order.
Iden Versio
As the daughter of Admiral Garrick Versio and the leader of the Empire's elite Inferno Squad, Iden Versio was an unmatched soldier and Imperial loyalist. When Iden saw her homeworld Vardos -- a planet that had always been loyal to the Empire -- be mercilessly attacked as part of Operation: Cinder, she realized she could no longer remain loyal to it.
Not only did Iden leave the Empire behind, but she joined the Rebel Alliance, and fought against the Imperial remnants, which included her father and her former Inferno Squad ally, Gideon Hask. Almost three decades later, Iden helped out the Resistance in their fight against the First Order, as well. Despite dedicating so much of her life and identity to the Empire, Iden had the guts to walk away and fight for a better galaxy.
Alexsandr Kallus
In one of Star Wars Rebels' most heartwarming moments, Kanan Jarrus acknowledged that Kallus risked everything when he defected from the Empire to help the Rebellion. But unlike most other defectors, Kallus did not just run away. He stayed within their ranks, pretending to remain loyal to them while actually feeding vital information to the Rebellion.
Kallus risked more than most as he remained in the belly of the beast and had the potential to be discovered by Grand Admiral Thrawn or the other Imperials at any moment. When his identity as Fulcrum was inevitably discovered, he continued to be brave, including when he fought alongside the Ghost crew in their efforts to liberate Lothal from Imperial control.
Sabine Wren
Sabine built formidable weapons that the Empire used against her own people. When Sabine spoke out against the Empire, her family did not stand with her but chose to remain loyal to the Empire instead. Defecting from the Empire cost Sabine her family and her place in Mandalorian society for a long time.
Against incredible odds, Sabine and the Ghost crew courageously took on the Empire and were integral to building the Rebellion. Not only did she show bravery through her defection and in how she stood up to the Empire, but in how she confronted her family and fellow Mandalorians who abandoned her.
Galen Erso
The Empire relied on Galen Erso's talents to develop the first Death Star's superlaser. Initially, Galen thought his research into kyber crystals and energy had to do with the Empire rebuilding the galaxy after the Clone Wars. Once he realized what his research was actually being used for, he and his family fled the Empire.
Orson Krennic dragged Galen back into the Empire against his will to finish his work. Galen pretended to be defeated and obedient, while he designed a secret fatal flaw in the Death Star. Galen's research made the planet-destroying superlaser possible, but his defection and sabotage also made the Death Star's destruction possible, and he achieved it all while working under the Empire's nose.
Bodhi Rook
By passing on Galen Erso's message about the Death Star to the Rebellion, Bodhi incurred the Empire's wrath and became the most wanted man in the galaxy. Both the Empire and the Rebellion engaged in a race to reach him first. The whole Empire wanted him dead and even rebels like Saw Gerrera didn't trust him.
Bodhi's bravery didn't stop there, as he risked his life -- and ultimately died -- so the Rebellion was able to receive the Death Star plans after the shield gate went up during the Battle of Scarif. Without Bodhi, the Rebellion never would never have known about the Death Star plans and the weakness that allowed the super-weapon to be destroyed.
Han Solo
Han Solo was kicked out of the Imperial Academy. After seeing the horrors of war while serving as an Imperial mudtrooper on Mimban, Han fled from the Empire with Chewbacca and Tobias Beckett's crew. However, Han's true courage didn't shine through until years after his defection during the Galactic Civil War.
He made the brave choice to risk his life by returning to the Death Star during the Battle of Yavin, a choice that saved Luke Skywalker's life and ensured the destruction of the first Death Star. Han also led the Rebellion on the forest moon of Endor and helped bring down the shield that allowed the Rebellion to destroy the second Death Star. Over time, he grew from an Imperial to a scoundrel and eventually one of the bravest rebel heroes in the fights against the Empire and the First Order.