U-3PO

U-3PO was a 3PO-series protocol droid who served the Alderaanian Diplomatic Corps. After Imperial agents altered his programming, the droid became an unwitting spy in the royal court of the planet Alderaan, and was assigned to the CR90 corvette Tantive IV in 1 BBY. After the corvette fled from the Battle of Scarif carrying the plans to the Death Star superweapon, the Empire used U-3PO to track the vessel to the Tatoo system.

The Imperial I-class Star Destroyer Devastator then attacked the Tantive IV, and the Star Destroyer fired upon the corvette, U-3PO followed the droids C-3PO and R2-D2 through the Tantive IV's main corridor before splitting off from them down a separate corridor. After the Empire captured the Tantive IV they discovered that U-3PO could provide no further useful information and that the Death Star plans were no longer aboard.

Text and facts from the “U-3PO” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.