Apo

Apo or APO may refer to:
* Apo, a god of mountains in Inca mythology
* Abdullah Öcalan, nicknamed "Apo", the leader of the Kurdistan Workers Party
* Acting Pilot Officer, the lowest commissioned officer rank in the Royal Air Force
* Acute Pulmonary Oedema, a medical condition affecting the lungs
* African Political Organization, the first major Coloured political organization in South Africa
* Alpha Phi Omega (ΑΦΩ), a coeducational service fraternity
* Amorphous polycycloolefin, a material used in optical disc substrates
* Apochromat, a lens that has greatly reduced chromatic aberration
* Apolipoprotein, a lipid-binding protein
* Army Post Office, the United States armed forces postal service
* Ausserparlamentarische Opposition (Extraparliamentary Opposition), a German part of the New Left movement
* Asamblea Popular de los Pueblos de Oaxaca

In biology:
* Apo structure, a macromolecule structure without a ligand or co-factor bound as opposed to a holo structure, which refers to an enzyme with its ligand or a co-factor bound.

In business:
* Advanced Planner and Optimizer, a Supply Chain Management computer system by German software giant SAP AG
* Agency purchase order
* American Community Properties Trust, from its AMEX ticker symbol
* Asian Productivity Organization
* The Association for Professional Observers, an association of fisheries observers

In music & entertainment:
* The Armenian Philharmonic Orchestra
* APO Hiking Society, a Filipino singing group
* Authorized Personnel Only, a fictional black-ops division of the CIA on the television series "Alias"
* Autopilot Off, a pop punk band from Orange County, New York

Places:
* Apo, Nigeria, a Local Government Area in Benue State, Nigeria
* Apo Island in the Philippines
* Apo-eup, a village in Gimcheon, South Korea
* Mount Apo, the Philippines' highest peak
* Apache Point Observatory, New Mexico
* Karaš River, from its ancient Latin name, "Apo"