- “Hello. I am C-3PO, human-cyborg relations. How might I serve you?”
- ―C-3PO introducing himself.
C-3PO is programmed for over thirty secondary functions besides protocol. He is cowardly, however, he has shown some instances of ingenuity and even deviance. C-3PO was rather polite and quirky towards his companions, especially R2-D2, although he could be sarcastic and indignant when mistreated by individuals like Jabba the Hutt. 3PO also has some knowledge on taunts.
C-3PO is known for his polite, fastidious, and worry-prone personality. As a droid, he exhibited much loyalty and commitment to his masters and sought to serve them to his best ability.
Unlike his astromech counterpart R2-D2, C-3PO liked to stick to routine and does not respond well to change. When placed in danger, C-3PO has a tendency to panic as shown on several occasions. Despite his loyalty and commitment, C-3PO is generally unable to lie or to keep secrets due his programming, although he was able to keep the fact that Anakin Skywalker and Padmé Amidala were husband and wife to himself. C-3PO's inability to lie came at a disadvantage when he and his companions were captured by Ewoks prior to the Battle of Endor.
- Multilingual: As a protocol droid, C-3PO is capable of fluently speaking over six million different forms of communication, including English, Ancient Askajian, B'rknaa language, Bimmini, Bith, Bocce, Binary, Ewokese, Gacerian, Gamorrese, Horansi, Huttese, Ithorese, Janguine, Jawa Trade language, Myneyrsh, Old Tarmidian, Psadan, Shyriiwook, Ssi-ruuvi, Talzzi, Ubese, Tusken, Yeb language, Yuuzhan Vong and Yuzzum.
- Master Pilot: As a protocol droid, C-3PO is highly skilled in piloting many types of flying craft.
The Phantom Menace
C-3PO was built on the desert planet of Tatooine by the young Anakin Skywalker, who was a slave to Watto before Jedi Master Qui-Gon Jinn freed him and took him back to Coruscant to be trained as a Jedi.
He was shown to Padmé Amidala and R2-D2 where he was at the time "Naked" (referred by R2-D2), as he had no coverings and his inner mechanisms were showing. He helped Anakin build a pod racer so he would enter the competition and win for Qui-Gon so they could gain parts to repair his ship. After Anakin told him he was now free, he was at the same to delighted for him but also disappointed because he would no longer finish working on him or give him coverings. Before leaving, Anakin promised to make sure his mother wouldn't sell him, which left him worried.
Attack of the Clones
C-3PO would not see Anakin again until ten years later where he had been given coverings and now lived on the Lars Farm with Shmi Skywalker who married Cliegg Lars.
When a message from Obi-Wan Kenobi informed he was in trouble, C-3PO accompanied Anakin, Padme and Artoo on a rescue mission to Geonosis. despite being told to stay with the ship, Artoo went out to follow them despite C-3PO trying to stop him. The two droids found their ways to the Droid factory where he lost his head and had it placed on the body of a B-1 Battle Droid while his body was given a Battle Droid head.
He engaged the Jedi in the Geonosis execution arena but was knocked down and trapped under another Battle Droid. R2-D2 showed up to retrieve his head and place it back onto his body. After the battle of Geonosis and the beginning of the Clone Wars, 3PO and R2 were the only two to witness Anakin and Padme's marriage.
Revenge of the Sith
By the time of the end of the Clone Wars, 3PO was fitted with gold plated coverings and became Padmé's personal protocol droid.
C-3P0 became witness to his maker's turn to the dark side of the Force when he accompanied Padmé to Mustafar, and Anakin, now the Sith Lord Darth Vader, used the Force to choke her into unconsciousness; whereupon C-3PO and R2-D2 took her to safety. When Obi-Wan returned to their spaceship, 3PO flew them to Polis Massa and witnessed the birth to the Skywalker twins, Luke and Leia, as well as Padmé's death. Shortly thereafter, C-3PO and R2-D2 were placed in the custody of Bail Organa, who gave the order to have C-3PO's memory erased to protect the twins from Palpatine.
A New Hope
Nineteen years after the rise of the Galactic Empire, C-3PO and his best friend R2-D2 have become members of the Rebel Alliance, he is also in the service of Leia Organa (unknown to him is the daughter of his creator, Anakin Skywalker; due to him having his memories unwillingly previously erased).
C-3PO appears along with R2-D2 in one episode of Sesame Street. The two meet up with Big Bird.
C-3PO makes a guest appearance with R2-D2 in "scavANTger hunt". Daniels did not reprise his role, and Artoo did not have the proper sound effects. Threepio claims to know street slang, and tells the main characters to "Step off, fools".
In the episode "Droids in Distress" 3PO and Artoo accompanied Minister Tua to Garel where he served as a translator for Amda Wabo. Upon their arrival, C-3PO and R2-D2 were present when the Rebels stole crates of T-7 Ion Disruptors for the Empire. during the gunfire against Zeb and the Stormtroopers, He boarded the Ghost with R2 and journeyed back to Lothal. In his panic, he contacted the Empire and gave away the Rebel's location. After engaging the Empire, the Rebels returned 3PO and R2 to Bail Organa.
C-3PO appeared in the attraction's queue with R2-D2 working on fixing a Starspeeder 3000 as well as appearing in the in-cabin load and unload safety videos.
In the revamped Star Tours, C-3PO appears in the attraction as the accidental pilot of the attraction in addition to appearing in the queue like the original attraction. When doing some routine checkups on a Starspeeder 1000, he is locked in the pilot's seat and is forced to take control of the vehicle, escape Imperial forces after a Rebel Spy on board and get said spy to safety.
C-3PO is a meetable character during the event. He also dances during the Hyperspace Hoopla.
From 1986 onwards, a voiceover from C-3PO and R2-D2 briefly welcomed riders on Disneyland's PeopleMover as the trains passed through the Star Tours show building.
- C-3PO has the first line in the original trilogy and the last line in the prequel trilogy; both in the same location, a corridor on the Tantive IV.
- He and R2-D2 are given the most attention and involvement of any character in the Star Wars saga outside of the Skywalker family.