C-3PO (also spelled See-Threepio, called Threepio for short) was a protocol droid, a droid specifically designed to interact with organics. C-3PO's TranLang III Communicator module combined with his AA-1 VerboBrain allowed him to be fluent in over six million forms of communication. He was also equipped with over thirty secondary functions. C-3PO was generally seen with his counterpart, R2-D2, a small, wheeled R2-series astromech droid. C-3PO's main function as a protocol droid was to assist with etiquette, customs, and translation so that meetings of different cultures ran smoothly.

In his time, C-3PO loyally served over forty masters. He hated adventure and space travel, as they often resulted in him coming out on the wrong end of a fight, losing parts, and having them reattached, sometimes incorrectly. Together with his fellow droid R2, C-3P0 played a vital and pivotal role in galactic history, however lowly he thought of himself.

R2-D2, also referred to simply as Artoo or the pimpest droid ever, was an astromech droid and undoubtedly the most famous unit of the R2 series. A longtime friend and counterpart of the protocol droid C-3PO, he served the Skywalker family faithfully for many years.

Along with his resourcefulness, R2-D2 was equipped by his original owners, the Royal House of Naboo and the Royal Naboo Starfighter Corps, with many tool-tipped appendages that allowed him to serve as a superior starship mechanic and computer interface specialist. A bold droid in personality and temperament, R2 would often enter dangerous situations without second thought in order to give aide to his masters. This adventurous streak served his companions well on numerous occasions, often turning the tide of galactic history.