Jyn Erso, also known by the aliases Lianna Hallik, Tanith Pontha, and Kestrel Dawn, was a human female soldier and former criminal who was a pivotal member of the Alliance to Restore the Republic, serving as a sergeant during their war against the Galactic Empire. Born in a Separatist prison on the icy planet Vallt in 22 BBY, Jyn was the daughter of Galen Erso, a scientist whose knowledge was sought by both the Galactic Republic and the Confederacy of Independent Systems. Rescued at six months old by her father's past friend Orson Krennic, Jyn spent the next several months living on Coruscant.
At the end of the Clone Wars, Jyn lived on the planet Lokori but traveled back to Coruscant during the formation of the Empire. When it was revealed that Galen's research for a supposed kyber crystal sustainable energy project was in fact being used to develop a superweapon, the Ersos, with the help of rebel Saw Gerrera, went into exile on the remote planet of Lah'mu.
Years later, their location was discovered by Krennic, who captured Galen so he could continue his work. Escaping with Gerrera, Jyn became a member of his extremist rebel faction but was ultimately abandoned at sixteen years old. Forced to survive on her own, Jyn developed various skills, including hand-to-hand combat.
In 0 BBY, Jyn was captured by the Rebel Alliance and sent on a mission to the Force-sacred world of Jedha to meet with Gerrera. Though she originally cared not for the Rebels' cause, after witnessing a hologram recording of her father regarding the Empire's superweapon, the Death Star, Jyn decided to help. Traveling to the storm-stricken planet of Eadu, Jyn attempted to rescue her father, but was unable to save him from the wounds he sustained from Alliance proton torpedoes. Knowing the Death Star plans were located on the Imperial world of Scarif, Jyn, accompanied by the newly formed "Rogue One" squad, infiltrated the Imperial complex on the planet and stole the technical readouts for the battle station. After transmitting the files to the Rebel fleet, Jyn was soon killed by an explosion produced by the Death Star's superlaser.
credit to wookieepedia