Daniels posing with the pieces of his C-3PO costume from the Original Trilogy.
During the production of the original Star Wars film, Daniels helped George Lucas develop the character, voice, and mannerisms of C-3PO. Aside from playing the fussy droid in all nine movies, Daniels has reprised the role frequently over the past three decades. He's donned the shiny suit for various promotional work, including hosting The Making of Star Wars; for appearances on The Muppet Show and Sesame Street; for The Star Wars Holiday Special; for commercials including Kenner toys, an anti-smoking PSA, and even a breakfast cereal based on the character; and for prequel tie-ins such as Star Wars Connections and The Science of Star Wars. He also voiced C-3PO in a radio drama based on the original trilogy; for the Christmas-themed Christmas in the Stars album; for the Disney theme-park attraction Star Tours; for the animated film The Lego Movie; and for animated series like Droids, Star Wars: Clone Wars, The Clone Wars, and Star Wars Rebels. He provided both narration and all character voices for the Dark Force Rising and The Last Command audio books.
Daniels has a cameo outside of the C-3PO costume in the Outlander nightclub scene early in Star Wars: Episode II Attack of the Clones as a character named Dannl Faytonni. Faytonni can also be seen at the Galaxies Opera House in Star Wars: Episode III Revenge of the Sith. He later played the enslaved worker Tak in Solo: A Star Wars Story.
Aside from portraying C-3PO and Dannl Faytonni, Anthony Daniels also played numerous minor characters such as CZ-3 in A New Hope. The exact number of such characters Daniels played is unknown.
He was the only cast member of the original trilogy to voice his character in all three episodes of National Public Radio's dramatizations of that trilogy. (While Mark Hamill voiced Luke Skywalker for both A New Hope and The Empire Strikes Back, and Billy Dee Williams voiced Lando Calrissian for The Empire Strikes Back, when the Return of the Jedi adaptation was recorded many years later, Hamill and Williams were replaced by Joshua Fardon and Arye Gross, respectively.)
Daniels also contributed the foreword to the collected scripts of the Return of the Jedi radio drama, as their author, Brian Daley, died just as the episodes were being recorded. Daniels' other Star Wars writings include The New Wonder Column for Star Wars Insider magazine and a comic-book adventure for C-3PO and R2-D2 entitled The Protocol Offensive, published by Dark Horse Comics.
In The Phantom Menace, Daniels did the voice work for C-3PO but did not physically appear in the movie, as the character was a puppet instead of a costume—a prototype version of the protocol droid controlled by someone else. He actually controlled the puppet for 2002's Attack of the Clones, but all prototype scenes were cut, with the droid's first appearance in the movie being Daniels in costume. In this movie and 2005's Revenge of the Sith, he also dubbed the vocal tracks for some scenes that used computer-generated imagery.
Daniels was the host and narrator of Star Wars: In Concert.
Daniels has returned to voice C-3PO in numerous animated projects, including Star Wars: The Clone Wars. Due to his years of experience with the droid, Daniels was allowed to go through scripts before voice recording on The Clone Wars with Supervising Director Dave Filoni. During these sessions, Daniels was allowed to suggest changes to dialogue to ensure it fit with C-3PO's personality. To Filoni, such changes gave the audience a more authentic preformance from a legacy actor.
In 2019, Daniels published an autobiography, I Am C-3PO: The Inside Story.