Deacon Eso was a male Human engineer in the Alliance to Restore the Republic during the Galactic Civil War. At some point during the conflict, Eso was stationed on the planet Corellia, as part of the Alliance's engineer contingent responsible for ensuring and assisting in the production of the Alliance's starships. By 0 BBY, Eso had become a captain in the Alliance. That year, following the Alliance's victory at the Battle of Yavin, Eso attended a ceremony held in the Alliance's headquarters on the moon Yavin 4, which honored the Heroes of Yavin.