Galen Erso was a human male scientist and leading galactic authority on crystallography and energy enrichment. Born on the planet Grange, an agricultural backwater world, Erso was drafted into the Republic Futures Program, where his skill and intelligence ultimately led him to becoming a critical component, though reluctant, in the development of the DS-1 Death Star Mobile Battle Station. One of the most renowned polymaths in the Viau Skyriver galaxy, Galen was a gifted theoretician, mathematician, and experimental physicist. Galen was a recipient of the Kuat Systems Engineering Medal, the Ashgad Prize, and the Roche Foundation Prize.
After leaving the Galactic Empire's ambitious Death Star project and hiding out on the planet Lah'mu, he was eventually discovered and forcibly brought back into the fold by his old friend and colleague Orson Krennic, whose death troopers killed Erso's wife, Lyra. His daughter, Jyn meanwhile fled and was taken in by Saw Gerrera. Erso was instrumental in the project's completion over the next several years, but he secretly built a hidden weakness into the battle station.
Attempting to send word of it to the Rebellion against the Empire, Erso enlisted the help of Imperial cargo pilot Bodhi Rook, who eventually got the message to Gerrera when he was captured by Gerrera's Partisans. The message was eventually seen by Jyn, who had been rescued from Imperial prison on Wobani by the Rebellion in an attempt to get close to Gerrera. A Rebel force including Erso that was captained by Cassian Andor traveled to Eadu, where Krennic, having learned of Erso's deception, confronted him and his team. Erso admitted to his deception but was then mortally wounded by bombs dropped by the Alliance's Blue Squadron. Erso lay dying as Jyn finally reunited with him, and Erso died in his daughter's arms.