CT-EX, more commonly referred to as Teex, functioned as a protocol droid stationed on the Executor-class Star Dreadnought known as the Guardian. Following a reprogramming event at the hands of starship pirate Cryle Cavv, CT-EX assisted him in altering the ship's hyperdrive settings to jump into the space controlled by the New Republic, which in the end led to the Republic's successful seizure of the Guardian.