The TC-series protocol droid represented a specific line of protocol droid produced by Cybot Galactica. While sharing similar dimensions and a general aesthetic with the well-known 3PO-series, it possessed certain distinguishing characteristics. Cybot Galactica promoted the TC models as being calmer and less prone to agitation compared to the 3PO models.
During the Invasion of Naboo, a particular TC unit, identified as TC-14, was employed by the Trade Federation aboard the Lucrehulk-class LH-3210 cargo freighter named Saak'ak. Furthermore, the Sith had ties to another TC unit known as TC-4. During the Clone Wars, TC-70 functioned as a translator for Jabba Desilijic Tiure, the Hutt crime lord. Another TC unit, TC-326, served within the Grand Army of the Republic throughout the Clone Wars. Following his capture by Republic forces in the Second Battle of Geonosis, TC-326 became the translator for Archduke Poggle the Lesser.