Aku can refer to:
- Aku, Nigeria, a town in Enugu State
- "Aku" (poem), a 1943 poem by Chairil Anwar
- Aku people, a minority ethnic group of Gambia
- Aku dialect, a dialect of Sierra Leone Krio
- Aku (Samurai Jack)
- The Hawaiian word for skipjack tuna
- Hal Lewis (Aku), a former morning air personality at KGMB (now KSSK), an AM station in Honolulu, Hawaii
- Aku Ankka (Finnish for Donald Duck), a Finnish weekly Disney comics magazine
- Aku Louhimies, Finnish film director and screenwriter
As an abbreviation, AKU can stand for:
- Aryabhatta Knowledge University, a university in the state of Bihar, India
- Adaptation kit upgrade, a mechanism for updating Windows Mobile
- Aga Khan University, an international Pakistani university
- Al-Kafaàt University, a University in Beirut, Lebanon
- Alkaptonuria, or black urine disease
- Amirkabir University of Technology, Tehran, Iran
- Algemene Kunstzijde Unie, a former Dutch company now called Akzo Nobel