FA, Fa or fa may refer to:

• Fa of Xia, King of China 1747–1728 BC
• Fa Ngum (1316–1393), founder and ruler of the Lao kingdom of Lan Xang
• Fa Ziying (1964–1999), Chinese serial killer

• Fa, Aude, a commune of the Aude département in France
• Friends Academy, Locust Valley, New York, USA

• Fa (musical note)
• Fa Yuiry, a fictional character in Mobile Suit Zeta Gundam
• Fantasy Advertiser, later FA, UK fanzine
• Firearms (video game), 1998
• Fur Affinity, a furry fandom-centric art community website

• Fa (philosophy), a Chinese concept
• Falange Auténtica, a Spanish political party
• Fisheries Agency, Taiwan

• Fa (letter) of the Arabic abjad
• Faʼ language, Bantu language of Cameroon
• fa, ISO 639-1 code of the Persian language

• Factor analysis, a statistical method
• Fanconi anemia, a genetic disease
• Fayalite, an olivine mineral
• Femtoampere (fA)
• Fluorescein angiography, for eye examination
• Folic acid, a B vitamin
• Fractional anisotropy, degree of anisotropy
• Friedreich's ataxia, a genetic disease
• Nikon FA, a camera

• Forschungsamt, Nazi German intelligence agency
• Frontal Aviation, Soviet Air Forces battlefield air defence
• Fleet Admiral, usually the highest rank of naval officers

• The Football Association, regulatory body, England
• First ascent, of a mountain
• Football association, a governing body for an association football

• ALCO FA, a US locomotive
• Toyota FA, a truck
• Area forecast, in aviation
• Ferrocarriles Argentinos, Argentine railways
• Safair, a South African airline, IATA code
• NZR F^A Class, New Zealand locomotive class

• F.A. or Intermediate of Arts, an academic diploma
• Fa (brand), of personal care products
• fa’ or Fall (unit), obsolete Scottish length unit
• Food Addicts in Recovery Anonymous (FA)
• FurAffinity, an art sharing website.

• Sweet F.A., UK slang meaning "nothing at all"