C. or c. may refer to:
- Century, sometimes abbreviated as c. or C., a period of 100 years
- Letter C, the third letter in the alphabet.
- Cent (currency), abbreviated c. or ¢, a monetary unit that equals 1⁄100 of the basic unit of many currencies
- Caius or Gaius, abbreviated as C., a common Latin praenomen
- Circa, abbreviated as c. (or ca., circ., cca, and cc.) a Latin word meaning "about" or "around"
- Abbreviation c. meaning "chapter" in legal citation
- Prefix c/c. (and cc/cc.) meaning "column(s)" as in-source-locator in old citations (example: "c130")