Con is a Latin preposition meaning "together with". It is very frequently used as the abbreviation of contra, which is a separate preposition. It may refer to:
* Confidence trick, also known as con, scam, or flim flam
* Con (TV series), a television show about confidence trickery
* Convention (meeting)
* Conference, e.g. "youth con"
* Convict, as in ex-con, a person who has been convicted of a crime
* Convicted felon, a person who has been convicted of a felony crime in a court of law
* Contact lens, in Hong Kong English
* Con, meaning, "congratulations" in the old language of Brutal.
* Conning tower, a raised platform on a ship or submarine, designed for use when conning (see above)
* Cornwall, England, via its Chapman code
* Concord Municipal Airport, in Concord, New Hampshire, via its International Air Transport Association airport code
* Continental Oil, via its ICAO airline designator
* Commonwealth of Nations, an association of primarily former British colonies
* Fan convention, e.g. "Comic-Con"
* Consider (MUD), the ability to evaluate an opponent in MUDs
* In Italian musical terms used in English, it indicates "with"