Cassio Tagge was a high-ranking human male officer during the reign of the Galactic Empire. Born into the wealthy and powerful Tagge family of Tepasi (the owners of TaggeCo), Tagge held the position of Chief of the Imperial Army; serving on the Joint Chiefs, he had access to the upper-levels of the Imperial Palace. In the early stages of the Galactic Civil War, he opposed the efforts of Wilhuff Tarkin and Conan Antonio Motti to base Imperial policy around the Death Star superweapon.

Following the Battle of Yavin and the destruction of the battlestation, Tagge was elevated to the rank of Grand General by Emperor Sheev Palpatine. As the new Supreme Commander of the Imperial Military, he relied on systems analysis and attempted to reorient Imperial strategy to rely on numerical superiority. Despite success in anti-piracy operations, his tenure was marked by his acrimonious relationship with Darth Vader, Dark Lord of the Sith—causing Tagge to increasingly rely on the cyberneticist Cylo as his enforcer. However, Cylo’s betrayal caused the Emperor to lose faith in Tagge, leading to his demotion and, soon after, his execution by Vader.