C-3PO (pronounced See-Threepio, called 3PO for short) is a character from the fictional Star Wars universe. He is a protocol droid - an android specifically designed to interact with organics - with a very proper manner and British accent when speaking in English, though he is, "fluent in over six million forms of communication." He is portrayed by actor Anthony Daniels.

C-3PO is generally seen with his counterpart, R2-D2, who is a small, wheeled astromech droid. His main function as a protocol droid is to assist with etiquette, customs, and translation so that meetings of different cultures run smoothly. He is very loyal to his masters (as his programming dictates) and has served over 40 since his creation.

C-3PO is one of the few characters to appear in all six of the Star Wars feature films, and one of the very few to be played six times by the same actor (voiced and played by Anthony Daniels). In The Phantom Menace, we learn that 3PO was built by Anakin Skywalker who would go on to become Darth Vader, Luke Skywalker's nemesis in the original series of films. Appearing mainly in a skeletal state in the film, he doesn't gain his coverings until Attack of the Clones. As revealed in Star Wars: Clone Wars, 3PO received his familiar gold plating from Padmé Amidala to better fit his role as her assistant. It is presumed he will have his memory wiped in Star Wars Episode III: Revenge of the Sith, as he doesn't seem to recognize Tatooine or the name Skywalker in A New Hope, although there is evidence that 3PO, in his capacity as a protocol droid, does have some expertise at concealing the truth. In Inside the Worlds of Star Wars Trilogy, 3PO is shown shutting down after seeing Anakin Skywalker's lightsaber, because his "protocol programming requires him to request that he shut down to protect his ex-owner's secrets".

He never makes it out of a movie completly intact, and hates adventure, (how he knows he has had an adventure is hard to tell). His motto is, "We're doomed!".

In 2004, C-3PO was inducted into the Robot Hall of Fame.