ONU may refer to:
People Lady Ōnu (died 724), Japanese noblewoman Onu (surname)
Organizations United Nations in other languages, e.g. French Organisation des Nations Unies, Spanish Organización de las Naciones Unidas and Portuguese Organização das Nações Unidas Olivet Nazarene University Ohio Northern University Organizacion de Narcotraficantes Unidos, a Puerto Rican criminal organization Odesa University, ( ONU), Ukraine
Other uses Onu (pronoun), Polish neopronoun Optical Network Unit, the IEEE term for Optical Network Terminal Order of Nunavut, civilian honor in Canada Unua language (ISO 639: onu), Austronesian language of Vanuatu