T4-O6, nicknamed T4, was an astromech droid built during the Great Galactic War, and which continued functioning into the succeeding Cold War between the Galactic Republic and the Sith Empire. Built specifically to cater to the needs of starships, T4 was an expert on all starship technology, ranging from starfighters to capital ships. The astro droid also possessed offensive capabilities, equipped with a blaster in his hull and a ray shield for protection.