FIN may refer to:

• Finland (ISO 3166-1 alpha-3-code: FIN), a Nordic country in Europe
• ICAO code for Finnair
• FASB Interpretation Number, an identifier for documents published by the Financial Accounting Standards Board
• Federazione Italiana Nuoto, the Italian Swimming Federation
• A FIN packet in the Transmission Control Protocol (TCP)
• Internationalist League of Norway (Norwegian: Forbundet Internasjonalen i Noreg)
• Force Identification Number, a four-character code used to identify uniformed police officers
• fin (band) British indie rock band. Name is spelt fiN (with a capital N)

A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluid media. Fins are also used to increase surface areas for heat transfer purposes, or simply as ornamentation.

Fín was an Irish Princess, who lived during the 7th century. She was a daughter or granddaughter of Colmán Rímid (died 604) of Cenél nEógain.

Cities is the third studio album by American alternative rock band Anberlin, released on February 20, 2007. The songs "Godspeed" and "The Unwinding Cable Car" were released as singles with accompanying music videos. The album debuted at No. 19 on the Billboard 200.

Fin (not to be confused with British rock band Fin) were a British alternative rock band formed in 1993, who achieved mild success on the independent circuit in the UK.