Ass may refer to:
- Ass people (Jasses, Ossetians abnd Burtasses), selfname of Alans (Scytho-Sarmatian tribes)
- Asinus, a subgenus of Equus that includes the donkey and other asses
- Donkey, Equus africanus asinus
- By extension, an insult meaning idiot
- Donkey, Equus africanus asinus
- North American English informal term for buttocks
- áss, one of the Æsir in Norse mythology
- Ass (album), by Badfinger
- In abstract algebra, Ass(M) denotes the collection of all associated primes of a module M
- AsS, the basic chemical formula for arsenic sulfide
ASS may stand for:
- ASS (car), a French car made from 1919 to 1920
- ASS (gene), a human gene that encodes for the enzyme argininosuccinate synthetase
- Acta Sanctae Sedis, a former Roman monthly publication and gazette of the Holy See
- Advanced SubStation Alpha, a subtitles editor in computing
- Advisory Service for Squatters, a non-profit group based in London, UK
- Agents of Secret Stuff, a 2010 action comedy film
- American Sociological Society, the founding name for the American Sociological Association
- Angle-Side-Side, an ambiguous proof in mathematics: see Congruence (geometry) - Congruence of triangles
- All-Star Superman, a comic book