Gau may refer to:
- Gau (German), German term for a shire (region)
- GAU, German acronym of Größter Anzunehmender Unfall (literally: worst imaginable accident, pronounced like the word Gau)
- Gau (Final Fantasy VI), fictional character
- Gau Island, an island in Fiji
- Sacred cow in Hinduism
- Chief Directorate of Artillery of the Russian Empire and Soviet Union
- General Assistance Unemployable a Washington State unemployment program
- Lokpriya Gopinath Bordoloi International Airport (IATA code GAU)
- Saint Gaugericus (Gau, Géry)
- Vladimir Gau, Russian painter
- Gun, aircraft unit, a series of US aircraft guns: GAU-2, GAU-4, GAU-7, GAU-8 Avenger, GAU-10, GAU-12 Equalizer, GAU-13, GAU-15, GAU-16, GAU-17 Minigun, GAU-18, GAU-19, GAU-21
