3C may refer to:
In astronomy:
- 3C, the Third Cambridge Catalogue of Radio Sources, an astronomical reference series
In business:
- Long March 3C, a 2008 Chinese orbital rocket
- 3C Records, a record label
- 3C (radio), a defunct digital radio station
- Team 3C Casalinghi Jet Androni Giocattoli, a defunct Italian professional cycling team
- 3C, the IATA code for defunct American airline RegionsAir
- Three-cent piece
- 3C (trade association) is an American trade association.
In computing:
- Three Cs (Compulsory, Capacity, and Conflict), three categories of CPU cache misses
- 3C, or Computer Control Company, Inc., a pioneering minicomputer company (1953–1966)
- Agile model: 3C (Card, Conversation, Confirmation)
- 3C, an abbreviation often used in Taiwan for "computer, communication, and consumer electronics"
In genetics:
- Alpha-tubulin 3C, a human gene
- 3C, or Chromosome conformation capture, a technique used in molecular biology
Substituted amphetamines (2C family analogues):
In places:
- Stalag III-C, a German Army World War II POW camp for Allied soldiers near Alt-Drewitz