Namrick in Portland Road, Hove, has been home to the Star Wars figure for over a decade having adorned it with a cardboard football scarf as part of the display.
However, workers at the shop discovered that the droid had disappeared and mourned the loss of the “amazing” figurine.
Tony McKinley, who has worked at Namrick for 20 years, said: “I’d raised him since he was just a young droid. There used to be a display with all sorts of things in there and he was the only one that was left.
“I’m a massive Whitehawk fan so we added the scarf, it was a wee bit of a laugh.
“It is what it is, it’s not the crime of the century but it’s still sad.”
Tony, 56, said he had originally bought “Threepio” from a nearby charity and he had been sat in the window for around 10 years.
He added that it was always nice to see the droid pop up on social media which he said happened every few years.
While cleaning at the shop, Tony discovered that the droid had been taken from the shop window but had no idea who could have stolen it or when exactly it happened.
C-3PO was made famous through the Star Wars film series where he was voiced by Anthony Daniels.