In Yevgeny Zamyatin's dystopian novel We, the mathematician narrator is identified as D-503.
D-503 is an engineer who builds the Integral, a spacecraft intended to carry the ideology of the One State to other worlds. He begins as a loyal citizen who records his thoughts in numbered entries, but encounters with the rebellious I-330 disrupt his mathematical certainty.
The One State assigns citizens alphanumeric designations rather than ordinary personal names. This naming system reflects the regime's desire to reduce individuality to measurable social function. Other important figures include O-90, who is connected to D-503, and R-13, a poet.
D-503 is sometimes incorrectly given the name of another character because Zamyatin's novel contains many distinctive codes. His designation begins with the letter D and includes the number 503. We was written in the 1920s and first published in English in 1924.