The Sauer is a tributary river to the Moselle, flowing through Belgium, Luxembourg and Germany.
Sauer is a German surname, see Sauer (surname). The word sauer means sour, acidic.
Sauer may also refer to:
- Sauer (Altenau), a river of North Rhine-Westphalia, Germany
- Sauer (Rhine), a river in France and Germany
- Sauer & Sohn (founded 1751), a German firearms manufacturer
- Sauer Castle, an architecturally significant house in Kansas City, Kansas (US)
- Sauer Commission (created 1947), a South African study of segregation policies
- C. F. Sauer Company (founded 1887), a cooking products manufacturer
- SIG Sauer, US arm of Swiss manufacturing firm Swiss Arms AG
- Paul Sauer Bridge, a highway bridge in South Africa
- Cube 2: Sauerbraten, a 2004 popular on-line game
- Sauer Van, a gas van used in the Sajmište concentration camp