AT may mean:
Aarne-Thompson classification system
AT Field, a force field in the anime Neon Genesis Evangelion
Acceptance test
Aero triangulation
Air Trecks, fictional inline skates in the manga and anime Air Gear
Alimentary tract
Allied Telesyn
Atmel Corporation
Anaerobic threshold
Análisis Transaccional (Spanish "Transactional analysis"), a psychological method
Anguilla, a World Meteorological Organization country code
Anti-tank weapons
Counter-terrorism, also known as "anti-terrorism" (AT)
Appalachian Trail
Aphex Twin
Appropriate Technology
Ashmore and Cartier Islands (FIPS 10-4 territory code and obsolete NATO country code
Assistive technology
IBM Personal Computer/AT
AT form factor for motherboards and computer cases
The common name for the 5-pin DIN keyboard connector
Ataxia telangiectasia, an immunodeficiency disorder
Atchison County, Kansas (county code)
Attack Team , a 2000 computer game
Audit trail
Austria's ISO, 2-letter country code
.at is the Internet country code