See: C3PO and C3PO & R2D2
Anthony Kingsley Daniels (born 21 February 1946) is an English actor, known for his role as the droid C3PO in the Star Wars series of films made between 1977 and 2005. Daniels and Kenneth Baker, who played R2D2, are the only actors credited as playing the same role in all six of the Star Wars films.
C-3PO (, nicknamed Threepio) is a fictional character from the Star Wars universe, who appears in both the original Star Wars films and the prequel trilogy. He is also a major character in the television show Star Wars: Droids, and appears frequently in the series' "Expanded Universe" of novels, comic books, and video games. C-3PO is one of the four characters to appear in all six of the Star Wars feature films, and one of only two characters portrayed by the same actor in all six installments of the series (the other being Kenneth Baker as R2D2). In all his various appearances, he is portrayed by Anthony Daniels.
C-3PO is a protocol droid designed to serve humans, and boasts that he is fluent "in over six million forms of communication." C3PO is generally seen with his long-time counterpart, R2D2, a small, quirky astromech droid. Threepio's main function as a protocol droid is to assist with etiquette, customs, and translation so that meetings of different cultures run smoothly. Together with his fellow droid R2D2, Threepio played a vital and pivotal role in the Galaxy's history.