A lot of people will interchange an "o" for a zero when speaking them aloud, like with phone numbers and postal codes, so I'm thinking this is the same here, but with nicknames like "threepio", I'm not so sure.

I'm looking for the canon answer here.

  • 27
    Google certainly thinks its "C-3PO" (O for Orange, not 0 for the balance of my bank account).
    – TZHX
    Apr 17, 2015 at 18:49
  • 15
    It always bothered me that they were 4 character serial numbers. That doesn't add up to very many unique droid names.
    – Sobrique
    Apr 17, 2015 at 19:56
  • 20
    @Sobrique I always assumed (for my own sanity) that they were the head or tail of a longer serial code. Much like git tags are frequently reduced to only a few characters instead of the full hash.
    – agweber
    Apr 17, 2015 at 20:08
  • 11
    @Sobrique actually, it's a five digit serial number. The dash itself is a character. Notice C-3PO vs. R2-D2, the dash is in a different place. And some types of droids had much longer names/codes.
    – Omegacron
    Apr 17, 2015 at 20:18
  • 3
    @fluffy thanks, but the only place I want to see The Phantom Menace is in the stomach of a Sarlacc Beast.
    – smci
    Apr 18, 2015 at 20:04

2 Answers 2


The script spells it with an 'O':

An explosion rocks the ship as two robots, Artoo-Detoo (R2-D2) and See-Threepio (C-3PO) struggle to make their way through the shaking, bouncing passageway. Both robots are old and battered. Artoo is a short, claw-armed tripod. His face is a mass of computer lights surrounding a radar eye. Threepio, on the other hand, is a tall, slender robot of human proportions. He has a gleaming bronze-like metallic surface of an Art Deco design.

Star Wars Episode IV: A New Hope (1977)

Although I can't find his designation used anywhere in the text of the novelization, the 1979 paperback has an inset featuring stills from the movie and short character bios; Threepio's designation appears there as "C-3PO" (with an 'O', not a '0'):

A faded scan of an old book

It's faded, but you can clearly see an 'O'.

  • 1
    Although I think you're right, where's the evidence that that's a O in that font and not a 0? Mar 8, 2018 at 22:00
  • @ThePopMachine While I can't be certain, the font appears to be either Futura or Twentieth Century, which have very distinctive O and 0 characters. The capital O in these fonts have an equal width and height. Dec 10, 2019 at 2:43
  • "Threepio" - now that raises the question of why it's not pronounced "three - pie - oh" instead of "three-pee-oh".
    – FreeMan
    Oct 20, 2023 at 17:55

StarWars.com, the scripts, and the novelization all explicitly say it is C-3PO.

To confirm this, I copy-pasted the text from the StarWars.com page shown below and then typed it out with a zero instead in a font that distinguishes the two characters. You can see the difference in fonts.

"C-3PO" – directly from starwars.com

"C-3P0" – typed with a zero-character


Similarly to this, I checked the novelization and the scripts. Searching for "C-3PO" returns numerous results. Searching for "C-3P0" returns none.

  • 10
    Another piece of evidence is that the URL on StarWars.com actually uses a lower-case 'o', which is clearly not a zero. Apr 18, 2015 at 19:16

Not the answer you're looking for? Browse other questions tagged or ask your own question.