Dau or DAU may refer to:

• Club Deportivo Árabe Unido
• Daily active users, a performance metric for the success of an Internet product
• Dau (surname)
• Dau (film), a biography of physicist Lev Landau
• DAU (project), a cross-sectional cinema and art project
• Dau, a barangay in Mabalacat, Pampanga, Philippines
• Dauair (ICAO code), a small, short-lived German airline
• Da'u County, or Dawu County, in Sichuan, China
• Daru Airport (IATA code), airport in Daru, Papua New Guinea
• Defense Acquisition University, a university under the United States Department of Defense located in Fort Belvoir, Virginia